Which equation correctly relates the heat of reaction to the standard heats of formation?
∆H° = ∆Hf ° (products) + ∆Hf ° (reactants)
∆H° + ∆Hf ° (products) = ∆Hf ° (reactants)
∆H° = ∆Hf ° (products) – ∆Hf ° (reactants)
∆H° – ∆Hf ° (reactants) = ∆Hf ° (products)

Answer:

[tex]_{40}^{103}Zr[/tex]

Explanation:

For any nuclear equation, we should utilize the law of mass conservation and the law of charge conservation. The sum of the masses on the left-hand side of the arrow should be equal to the sum of the masses on the right-hand side of the arrow (those are the superscripts for each nucleus). Similarly, the sums of charges should be equal (this is the law of charge conservation).

Let's say that the missing species is X with a mass of 'M' and charge of 'Z':

[tex]_{94}^{239}Pu+_0^1n\rightarrow _Z^MX+_{54}^{134}Xe+3_0^1n[/tex]

Find mass applying the mass balance law:

[tex]239+1=M+134+3\cdot1\\240 = M+137\\M=240 -137\\M=103[/tex]

This means our particle X has a mass of 103. Let's find the atomic number (the charge) same way:

[tex]94+0=Z+54+3\cdot0\\94=Z+54\\Z=94-54=40[/tex]

The atomic number of our nucleus is 40. That said, we have:

[tex]_{40}^{103}X[/tex]

Find the element in the periodic table with Z = 40. This is Zr. Meaning we can now identify it fully:

[tex]_{40}^{103}Zr[/tex]

Answer:

The correct option is:

D) starting to move and then increasing speed

Explanation:

The speed of the racehorse is given by the slope of the given Distance-time graph.

Speed = Distance/time = Slope of the graph

The slope of the graph keeps increasing.

Hence, the speed of the racehore is increasing.

The distance moved is zero at t=0. Hence, the racehorse has started to move from rest.

Answer:

D

Explanation:

I TOOK IT ON USA TEST PREP

Answer:

Mass of compound 1 is 0.7144g

Explanation:

1 mole of liposomes =22.4L

20mL (0.02L) of liposomes = 0.02/22.4 = 0.000893mole

Number of moles = Mass/Molecular Weight (MW)

Mass = Number of moles × MW = 0.000893 × 800 = 0.7144g

Answer:The last time levels of atmospheric carbon dioxide were this high came during the Pliocene Epoch, which extended from about 5.3 million to 2.6 million years ago

The amount of nutrients present in the tropic level is called the living state.

The accurate answer is very complicated as the amount of carbon dioxide is changes gradually every day. Therefore the exact date to the same ratio of carbon dioxide is difficult to tell.

In my opinion, the amount of carbon dioxide is high as it if for today is 20 years ago when ozone later starts depleting.

Hence, the correct answer is 20 years ago.

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Balancing the chemical equation CH₄ + O₂ → CO₂ + H₂O involves making sure that the number of atoms for each element is the same on both sides of the equation. The balanced equation is CH₄ + 2O₂ → CO₂ + 2H₂O.

To balance the given chemical equation CH₄ + O₂ → CO₂ + H₂O, start by looking at the number of atoms of each type on both sides of the equation. In the case of methane (CH₄), there is one carbon (C) atom and four hydrogen (H) atoms. On the product side, we have one carbon and two hydrogens in water (H2O), and one carbon in carbon dioxide (CO₂). Two waters must be produced to balance the hydrogen on both sides. This alteration however, affects the oxygen balance. Now, there are two oxygen atoms in CO₂ and one in H₂O (total of 4) on the product side. Hence, there should be 2 O₂ molecules on the reactant side. The balanced equation is thus CH₄ + 2O₂ → CO₂ + 2H₂O.

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The balanced equation is CH₄ + 2 O₂ → CO₂ + 2 H₂O.

To balance the chemical equation CH₄ + O₂ → CO₂ + H₂O, follow these steps:

The balanced chemical equation is CH₄ + 2 O₂ → CO₂ + 2 H₂O. Remember, it’s crucial not to alter the chemical formulas, only the coefficients in front of them to balance the equation.

Answer:

Polychlorinated Biphenyls.

Explanation:

Polychlorinated Biphenyls are man-made chemicals. They are solids, and oily liquid in structure with no taste or small, yellow to clear in color. PCBs are present as a mixture, and very stable at an extreme pressure, and temperature. Basically they are used in electrical equipment such as transformers, and capacitors. High level of PCBs can cause broad spectrum of effects in humans, for example:

1) Increase some liver enzyme level, and cause hepatic damage.

2) Respiratory problems.

3) Dermal lesions.

Answer:

Amount of CO required is 157.5 g

Explanation:

Molecular mass of Fe = 55.845 g/mol

Amount of Fe = 209.7 g

[tex]Mol\ of\ Fe=\frac{209.7}{55.845} \\=3.75\ mol[/tex]

Balanced reaction of reduction of Fe2O3 is as follows:

[tex]Fe_2O_3(s) + 3CO (g)\rightarrow 2Fe(s)+3CO_2(g)[/tex]

From the balanced reaction, 2 mol of Fe is produced by 3 mol of CO.

Therefore, 3.75 mol of Fe will be produced by,

                                                     [tex]\frac{3}{2} \times 3.75 = 5.625\ mol\ CO[/tex]

Relation between mass and mol is as follows:

Mass = Mol × Molecular formula

Molecular mass of CO = 28 g/mol

Grams of CO required = 5.625 mol × 28 g/mol

                                      = 157.5 g

Amount of CO required is 157.5 g.

Answer:

There are 157.8 grams of CO needed.

Explanation:

Step 1: Data given

Mass of Fe produced = 209.7 grams

Molar mass of Fe2O3 = 159.69 g/mol

Molar mass of Fe = 55.845 g/mol

Step 2: The balanced equation

3CO + Fe2O3 → 2Fe + 3CO2

Step 3: Calculate Moles of Fe

Moles Fe = mass Fe / molar mass Fe

Moles Fe = 209.7 grams / 55.845 g/mol

Moles Fe = 3.755 moles

Step 4: Calculate moles of CO

For 3 moles of CO we need 1 mol of Fe2O3 to produce 2 moles Fe and 3 moles of CO2

For 3.755 moles of Fe we need  3.755 *3/2 = 5.6325 moles of CO

Step 5: Calculate mass of CO

Mass CO = moles CO * molar mass CO

Mass CO = 5.6325 * 28.01 g/mol

Mass CO = 157.8 grams

There are 157.8 grams of CO needed.

Answer:

B. He should report the accident and leave the area.

Explanation:

Noxious gases are harmful and might cause hallucination or even death. Examples of such gases carbon monoxide (CO) and Ammonia gas (NH3).  

Let's look at all the options

Therefore,  He should report the accident and leave the area.

Answer:

b

Explanation:

Answer:

A. 630mL

Explanation:

The combined gas law says:

P₁V₁/T₁ = P₂V₂/T₂

Where P₁ is 2,4 atm; V₁ is 250mL; T₁ is 15+273,15 = 288,15K; P₂ is 1,0 atm; V₂ is the final volume; T₂ is 27°C; 27+273,15 = 300,15K.

Thus:

2,4atm×250mL/288,15K = 1,0atm×V₂/300,15K

V₂ = 625mL ≈ A. 630mL

I hope it helps!

Answer:

[tex]\large \boxed{\text{A. 620mL}}[/tex]

Explanation:

We can use the Combined Gas Laws to solve this problem

Data

p₁ = 2.4 atm;  p₂ = 1.0 atm

V₁ = 250 mL; V₂ = ?

T₁ = 15°C;       T₂ = 27 °C

Calculations

(a) Convert the temperatures to kelvins

T₁ = (15 + 273.15) K = 288.15 K

T₂ = (27 + 273.15) K = 300.15 K

(b) Calculate the new volume

[tex]\begin{array}{rcl}\dfrac{p_{1}V_{1} }{T_{1}} & = & \dfrac{p_{2}V_{2}}{T_{2}}\\\\\dfrac{\text{2.4 atm $\times$ 250 mL}}{\text{288.15 K}} & = & \dfrac{\text{1.0 atm} \times V_{2}}{\text{300.15 K}}\\\\\text{2.08 mL} & = & \dfrac{V_{2}}{300.15}\\\\V_{2} & = & \textbf{620 mL}\\\end{array}\\\text{The volume of the bubble when it reaches the surface is $\large \boxed{\textbf{620 mL}}$}[/tex]

Answer:

d. 103.3

Explanation:

In the given question, the National Weather Service routinely supplies atmospheric pressure data to help pilots set their altimeters. And the units of atmospheric pressure used for reporting the atmospheric pressure data are inches of mercury. For a barometric pressure of 30.51 inches of mercury, we can calculate the pressure in kPa as follow:

In principle, 3.386 kPa is equivalent to the atmospheric pressure of 1 inch of mercury. Thus, 30.51 inches of mercury is equivalent to 30.51 in *(3.386 kPa/1 in) = 103.307 kPa.

Therefore, a barometric pressure of 30.51 inches of mercury corresponds to _____103.3_____ kPa.

Answer : The mass of sucrose added to water will be, 189.0 grams.

Explanation :

As we are given that 9 % solution (mass per volume) that means 9 grams of sucrose present in 100 mL volume of solution.

Total given volume of solution = 2.1 L = 2100 mL    (1 L = 1000 mL)

Now we have to determine the mass of sucrose in solution.

As, 100 mL of solution contains 9 grams of sucrose

So, 2100 mL of solution contains [tex]\frac{2100mL}{100mL}\times 9g=189.0[/tex] grams of sucrose

Therefore, the mass of sucrose added to water will be, 189.0 grams.

The region associated with electromagnetic spectrum  which contains  light at frequencies and wavelengths that stimulates the rod and cones in the human eye is recognized as the visible region of the electromagnetic spectrum. The eye makes  the association  with some selected portions of that visible region through color.

Energy is inversely proportional to wavelength and it is directly proportional to the frequency.As the frequency and wavelength are related by a constant (c) we can also write the energy in terms of wavelength by the equation  [tex]E = \frac{hc}{\lambda}[/tex].

where h is a Planck's constant,

c is the velocity of the light.

Final answer:

The initial amount of gas X does not affect the equilibrium composition of gaseous products at a constant temperature, but more of solid Z will be formed until equilibrium is reached again.

Explanation:

The question concerns how the initial amount of a gas, X, affects the equilibrium quantities when it decomposes to form another gas, Y, and a solid, Z, according to the reaction 2X(g) ⇌ Y(g) + Z(s).

In an equilibrium involving a heterogeneous mixture of gases and solids at a constant temperature, the presence of a solid does not affect the equilibrium composition of the gaseous phase. Whether a small or large amount of the solid is present, the equilibrium composition of the gas remains unchanged.

This is because solids and liquids are pure substances with fixed densities and their concentrations are not included in the equilibrium constant expression. Hence, adding more X(g) would not change the equilibrium concentrations of Y(g), but it would lead to more Z(s) being formed until the equilibrium is re-established.

Answer:

to the left beaker

Explanation:

In the system above, we have two beakers containing different concentrations of glucose. In addition, the two beakers are separated by a permeable membrane which can allow the movement of glucose from one beaker to another. In order to attain equilibrium conditions, there will be a movement of glucose from the beaker with high glucose concentration (right beaker) to the beaker with low glucose concentration (left beaker).

Answer:

Rafter also called roof joist.

Explanation:

In roof framing, a rafter serves as the structural member that supports the building's roof. It is part of a rigid structure that is essential for the stability of the roof. Historically, other elements like engaged columns and buttresses were also used to support and stabilize the building structure.

With roof framing, a rafter is a structural member that supports the roof of a building. A rafter is part of a rigid structure formed of relatively slender pieces, which are typically joined together to support the roof. This is critical in roofing as it helps distribute the weight of the roof and ensures the stability of the building.

The history of roof construction shows that the types of construction varied based on the available natural materials. Load-bearing walls played a vital role in supporting the roofs and had to be constructed strong enough not only to support themselves but also the roof. If the roof span was too large, the walls could be pushed out and collapse.

Answer:metallic bond

Explanation:

The metallic bond consists of a layer of valence electrons electrostatically attracted to positive metal ions. Hence in a metal such as barium, electrons bind the metal ions together in the metallic crystal lattice of the element.

Answer:

V = 22.42 L/mol

N₂ and H₂ Same molar Volume at STP

Explanation:

Data Given:

molar volume of N₂ at STP = 22.42 L/mol

Calculation of molar volume of N₂ at STP  = ?

Comparison of molar volume of H₂ and N₂ = ?

Solution:

Molar Volume of Gas:

The volume occupied by 1 mole of any gas at standard temperature and pressure and it is always equal to 22.42 L/ mol

Molar volume can be calculated by using ideal gas formula  

                               PV = nRT

Rearrange the equation for Volume

                            V = nRT / P . . . . . . . . . (1)

where

P = pressure

V = Volume

T= Temperature

n = Number of moles

R = ideal gas constant

Standard values

P = 1 atm

T = 273 K

n = 1 mole

R = 0.08206 L.atm / mol. K

Now put the value in formula (1) to calculate volume for 1 mole of N₂

                   V = 1 x 273 K x 0.08206 L.atm / mol. K / 1 atm

                   V = 22.42 L/mol

Now if we look for the above calculation it will be the same for H₂ or any gas. so if we compare the molar volume of 1 mole N₂ and H₂ it will be the same at STP.

Answer: An increase in the ratio of insulin to glucagon will increase the activity of --

- Acetyl-CoA carboxylase(+)

-Phosphofructokinase PFK2(+)

-Glycogen synthase(+)

- Hormone sensitive lipase (-). The hormone sensitive lipase activity is not increased with increased insulin activity.

Explanation: increased insulin - glucagon ratio is usually high in fed state.Insulin helps the cells absorb glucose, reducing blood sugar and providing the cells with glucose for energy. When blood sugar levels are too low, the pancreas releases glucagon. Glucagon instructs the liver to release stored glucose, which causes blood sugar to rise.

Answer:

A chemical formula tells us the number of atoms of each element in a compound. It contains the symbols of the atoms of the elements present in the compound as well as how many there are for each element in the form of subscripts.

Explanation:

EXAMPLES:

H2SO4 : Sulfuric Acid. CH4 : Methane.

C12H22O11 : Sucrose. C3H8 : Propane.

NaHCO3 : Baking Soda. F : Fluoride. F2 : Fluoride.

H2O2 : Peroxide.

C8H10N4O2 : Caffeine.

C9H8O4 : Aspirin.

Zn(NO3)2 : Zinc. CO : Carbon Monoxide. NaOH : Sodium Hydroxide. ...

CnH2nOn : Sugar.

Answer:

0.098 moles H₂S

Explanation:

The reaction that takes place is

We can express the equilibrium constant as:

With the volume we can calculate the equilibrium concentration of H₂:

The stoichiometric ratio tells us that the concentration of S₂ is half of the concentration of H₂:

Now we can calculate [H₂S]:

So 0.013 M is the concentration of H₂S at equilibrium.

Initial moles of H₂S - Moles of H₂S that reacted into H₂ = Moles of H₂S at equilibrium

Initial moles of H₂S - 0.072 mol = 0.026 mol

Initial moles of H₂S = 0.098 moles H₂S

The number of moles of H2S initially added to the flask is 0.036 mol, calculated based on the number of moles of H2 gas (0.072 mol) obtained at equilibrium by assuming that each mole of H2S gives two moles of H2.

This question deals with the concept of chemical equilibrium in the reaction of hydrogen sulfide gas (H2S). It's assumed in the question that H2S gas dissociates into H2 and S2 according to the equation: H2S(g) ⇌ 2H2(g) + S2(g). When 0.072 mol of H2 is obtained at equilibrium, it implies that each mole of H2S gives two moles of H2. Therefore, the number of moles of H2S that were originally added to the flask would be half of the moles of H2 obtained at the equilibrium. Hence, the moles of H2S originally added to the flask are 0.072 / 2 = 0.036 mol.

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Answer:

B. produces H⁺ in solution.

Explanation:

Arrhenius theory:-

The Arrhenius theory was introduced introduced by Swedish scientist named Svante Arrhenius in 1887.

According to the theory, acids are the substances which dissociate in the aqueous medium to produce electrically charged atoms ( may be molecule). Out of these species furnished, one must be a proton or the hydrogen ion, [tex]H^+[/tex].

Base are the substances which dissociate in the aqueous medium to produce electrically charged atoms ( may be molecule). Out of these species furnished, one must be a hydroxide ion, [tex]OH^-[/tex].

Hence, the correct option is:- B. produces H⁺ in solution.

According to Arrhenius's theory, an acid is described as B. produces H⁺ in solution.

Arrhenius defined acids as substances that, when dissolved in water, increase the concentration of hydrogen ions (H⁺) in the solution. This definition is based on the idea that acids dissociate in water to release H⁺ ions, which then combine with water molecules to form hydronium ions (H₃O⁺).

For example, when hydrochloric acid (HCl) is dissolved in water, it dissociates into H⁺ and Cl⁻ ions. The H⁺ ions increase the acidity of the solution. This characteristic is central to the Arrhenius definition of acids, distinguishing them from bases, which are defined by their ability to produce OH⁻ ions in solution.

While other definitions of acids, such as Brønsted-Lowry, describe acids as proton donors, Arrhenius specifically focuses on the increase of H⁺ ions in aqueous solutions.

Answer:

The correct option is D ((+)70 mV)

Explanation:

IF an Axonal Membrane transiently becomes very permeable to Na+ ions then the membrane potential of the cell wall will approach (+)70 mV.

Answer:

For producing epinephrine , tyrosine is required .

Explanation:

Epinephrine is produced  in  adrenal medulla, where the amino acid tyrosine is transformed to norepinephrine. An enzyme known as phenylethanolamine N-methyltransferase catalyzes the methylation of norepinephrine to epinephrine.

Answer:

Hypothesis

Explanation:

The following steps are applicable when we wish to prove a specific fact:

In the context of this problem, we're at the first step where we make a hypothesis.

Answer:

whats expert verified????

Explanation:

Answer:

Depends on the conditions of reaction.

Explanation:

Any element or compound that enters into a chemical reaction can undergoes any process depending of the conditions of reaction, for example, temperature, pressure, medium, among others.

A chemical reaction is a process in which any substance, element or process undergoes chemical and physical changes.

In chemical reaction we have reactants, that is the innitial or starting elements or compounds; products which are the result of the reaction between the reactants and we might see physical changes.

For example, if we do a reaction betwenn Iron and oxygen:

4Fe + 3O2 --------> 2Fe2O3

Iron and oxygen reacts and creates a new product. This is the iron oxyde, which is a physical change too, and you can see that for a color change.

Depending on conditions, we can have several types of chemical reaction, such as synthesis, decomposition, single displacement, double displacement, equilibrium reactions, acid - base reactions among others.

In a chemical reaction, a reactant undergoes a process where it is converted into a product. The sequence of these steps is called the reaction mechanism. The reaction's rate is determined by the rate of the slowest step in the mechanism.

An element or compound that enters into a chemical reaction undergoes a process wherein it is converted into a different substance. This element or compound is called the reactant, and the new substance formed is called the product.

Chemical reactions occur when two or more atoms bond together to form molecules or when bonded atoms are broken apart. The sequence of individual steps by which reactants are converted into products during the course of a reaction is called the reaction mechanism.

The overall rate of a reaction is determined by the rate of the slowest step in its mechanism, called the rate-determining step. Chemical reactions can release or absorb heat, called exothermic and endothermic processes respectively.

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Answer: Mass of H2 liberated = 0.039g;

Mass of NaH that reacted = 0.468g

Note: This is the complete question (Binary compounds of alkali metals and hydrogen react with water to liberate H2(g). The H2 from the reaction of a sample of NaH with an excess of water fills a volume of 0.510 L above the water. The temperature of the gas is 35 ∘C and the total pressure is 755mmHg . Find the mass of H2 liberated and the mass of NaH that reacted.)

Explanation:

The equation of the reaction is NaH + H2O ---> NaOH + H2O

molar mass of NaH = 24g, molar mass of H2 = 2g

First, The volume, V1, of the gas produced at standard conditions (s.t.p.) is determined using the general gas equation; P1V1/T1 = P2V2/T2

Making V1 subject of the formula; V1 = P2V2T1/P1T2

P1 = 760mHg, P2 = 755mmHg, V1 = ?, V2 = 0.5L, T1 = 0∘C  = 273K, T2 = 35 ∘C = 308K

V1 = 755*0.5*273/(760*308) = 0.44L

1 mole or 22.4L of H2 has a mass of 2g;

mass of 0.44L of H2 = 2*0.44/22.4 = 0.039g

From the equation of the reaction, 2g of H2 is produced by 24g of NaH at s.t. p.

0.039g of H2 will be produced by 0.039*24/2 = 0.468g of NaH

The age of a rock with a mass ratio of argon-40 to potassium-40 of 4.2, and a half-life of potassium-40 of 1.27×109 years, is calculated to be approximately 1.7 billion years old using the potassium-argon dating method.

Calculating Rock Age Using Potassium-Argon Dating

The question asks for the age of a rock, given that the mass ratio of argon-40 (40Ar) to potassium-40 (40K) is 4.2. To find the age of the rock using the potassium-argon dating method, we can apply the concept that 40K decays into 40Ar with a known half-life. This half-life is given as 1.27×109 years.

Using the given mass ratio of 40Ar to 40K, which is 4.2, we can estimate the number of half-lives that have passed. Each half-life passed will result in the remaining 40K being half of what it was before and an increase in 40Ar. We can express the ratio in terms of the decay equation:

NAr / NK = (e−0.693t/T) / (1 − e−0.693t/T)

Where NAr is the amount of 40Ar, NK is the amount of remaining 40K, t is the age of the rock, and T is the half-life of 40K. Solving for t using the given ratio and half-life, we find that the rock is approximately 1.7 billion years old.

Answer:

a. 0.28 L

Explanation:

At constant pressure and number of moles, Using Charle's law  

[tex]\frac {V_1}{T_1}=\frac {V_2}{T_2}[/tex]

Given ,  

V₁ = 0.25 L

V₂ = ?

T₁ = 0 °C

T₂ = 35 °C  

The conversion of T( °C) to T(K) is shown below:

T(K) = T( °C) + 273.15  

So,  

T₁ = (0 + 273.15) K = 273.15 K  

T₂ = (35 + 273.15) K = 308.15 K  

Using above equation as:

[tex]\frac{0.25}{273.15}=\frac{V_2}{308.15}[/tex]

[tex]V_2=\frac{0.25\cdot \:308.15}{273.15}[/tex]

New volume = 0.28 L

Answer:

Explanation:

a. What is the mass number of the particle emitted from the nucleus during beta minus (β–) decay?

zero

The beta radiations are emitted in this reaction. The one electron is ejected and neutron is converted into proton.

⁴₆C → ¹⁴₇N + ⁰₋₁e

b. What kind of charge does the particle emitted from the nucleus during beta minus (β–) decay have?

Negative charge

Electron is emitted during beta decay and it carry negative charge.

c. What is another name for a beta minus (β–) particle?

Electron

During beta minus decay electron is emitted and neutron is converted into proton.

d. Write the balanced equation for the alpha decay that is below the “Show Equation.” Label the parent, daughter, and beta particle.

Equation is missing

a. What happens in the nucleus of an atom when an alpha particle is emitted?

When atom undergoes the alpha emission the original atom convert into the atom having mass number less than 4  and atomic number less than 2 as compared to the starting atom.

b. b. What happens in the nucleus of an atom when a beta particle is emitted?

When nucleus emit the beta particle neutron is converted into proton and this proton stay into the nucleus while at the same time electron is emitted. Thus atomic number is increased by one.

⁴₆C → ¹⁴₇N + ⁰₋₁e

Answer:

Niels Bohr states that the line spectrum of the hydrogen atom by assuming that the electron revolve in circular paths and that the paths  have an allowable radii. ...

Explanation:

discuss the origin of the line citing the bohr theory of the atom specify any energy transitions that are applicable

Niels Bohr states that the line spectrum of the hydrogen atom by assuming that the electron revolve in circular orbits and that orbits have an allowable radii. ... an absorption spectrum is produced, dark lines in the same position as the bright lines in the emission spectrum of an element are produced.

Bohr Atomic Model. Bohr Atomic Model : In 1913 Bohr proposed his quantized shell model of the atom to explain how electrons can have stable orbits around the nucleus. ... The atom will be stable in the state with the smallest orbit

Bohr explains to us that electron revolve round the nuclues of an atom and possess energy levels. they can change energy levels