Mendeleev is the father of periodic table based on the mass number of elements. The elements placed in this old periodic table was, hydrogen and lithium in a group, and Be, Mg, Al, S, Cl, Ca etc.
What is periodic table?Periodic table is a classification of all the elements discovered yet. There are groups which are vertical column with elements of similar properties. The periodic table was first introduced by Dimitri Mendeleev.
But Mendeleev was classified the elements based on the increasing order of mass number. But later it was modified as it is now based on the atomic number of elements.
Due to the discrepancies found in Mendeleev's periodic table Mossley modified the table and proposed that the atomic properties are based on the atomic number.
There were only about 63 elements in the old periodic table which included the elements hydrogen, Li, S, Mg, Ca, Na, N, O,C, some of the transition elements Ti. V, Cr, Mn etc.
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Suppose the innermost orbit an electron can occupy has an energy level of -19 eV. Based on the absorption spectrum shown below, what is the energy of energy level 4?
The energy of the 4th energy level, taking into account the shift in energy levels in the given problem, is -6.25 eV.
Explanation:The energy levels of an electron in an atom are quantized, meaning they can only have certain specific values. The question states that the innermost orbit of an electron has an energy level of -19 eV.
In a regular hydrogen atom, the ground state or the lowest energy state is -13.6 eV. If we consider the absorption spectrum, it provides information about the energy required for the electron to move from one energy state to another.
Given that the innermost energy state (n = 1) is -19 eV and not the regular -13.6 eV, it implies that energy levels of the hydrogen atom have been shifted by a constant value. The difference, i.e., -19 eV - (-13.6 eV) = -5.4 eV needs to be considered.
So, for the 4th energy level, E4, it should be E4 = (-13.6 eV / 4²) - 5.4 eV = -0.85 - 5.4 = -6.25 eV. Note, the energy decreases as we move from the 1st to 4th energy level, hence the negative sign.
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The major portion of an atom’s volume is(based on the gold foil experiment)?
Will all cars have roughly the same amount of force available
What physical properties would a pencil lead have
A 0.784 g sample of magnesium is added to a 250 ml flask and dissolved in 150 ml of water. magnesium hydroxide obtained from the reaction required 215.0 ml of 0.300 m hydrochloric acid to completely react. how many moles of hcl were used?
A lot of values are given but we must focus only on HCl.
There are 215 mL (0.215 L) of 0.300 M HCl that was completely used. We must remember the moles is simply the product of volume and molarity, that is:
number of moles = 0.215 L * 0.300 M
number of moles= 0.0645 moles HCl
Sublimation and boiling both happen at the surface of the substance.
a. True
b. False
What element has its 7 valence electrons in energy level 4 in s and p orbitals?
Which is a pure substance? A. sugar B. trail mix C. leaf salad D. sugar water
Answer:
A
Explanation:
Give an example of a two phase mixture and describe how you would separate the substances
Why is identifying unknown compounds important to chemistry?
Final answer:
Identifying unknown compounds is crucial in chemistry as it helps determine their composition, structure, and properties. This knowledge is essential for predicting behavior, reactivity, and potential applications of compounds.
Explanation:
Identifying unknown compounds is important to chemistry because it allows scientists to determine the composition, structure, and properties of those compounds. By knowing the elements present in a compound, their relative amounts, and the molecular or empirical formula of the compound, chemists can make predictions about its behavior, reactivity, and potential applications. For example, knowing the composition of a compound can help scientists understand its toxicity, stability, solubility, and potential uses in various industries.
The carbon atoms in large complex molecules are bonded to other atoms with
In the science lab, students are testing solutions as acids or bases. the ph level of solution "x" was determined to be an 8. what is solution "x"?
The wall of the flask is periodically rinsed with the previously boiled deionized water from the wash bottle. does this titrimetric technique result in an increase, a decrease, or have no effect on the reported acetic acid in the vinegar
Write the element symbol for the element with the abbreviated electron configuration [ne]3s23p2.
A molecule that is composed only of chains and rings of hydrogen and carbon is called a
What do the words in this group have in common biology chemistry anatomy nuclear physics?
Biology, chemistry, anatomy, and nuclear physics are different branches within the field of science.
Explanation:The words biology, chemistry, anatomy, and nuclear physics all belong to the field of science. They are different branches or subdisciplines within the broader category of science. Biology is the study of living organisms and their interactions with the environment. Chemistry focuses on the composition, structure, properties, and changes of substances. Anatomy is the study of the structure of organisms, especially the human body. Nuclear physics is a branch of physics that studies atomic nuclei and their interactions.
Who was the first to state the concept of an atom?
Answer:
The answer would be D. Democritus.
Explanation:
He was the first to state the concept of an atom.
Consider the chemical equilibrium of the following reaction CH3COOH CH3COO– (aq) + H+(aq) What will happen to the chemical equilibrium of the solution if CH3COONa is added? The equilibrium will shifts to the right. The equilibrium will shifts to the left. The equilibrium will be unaffected. The equilibrium will be lost.
Answer: The equilibrium will shifts to the left.
Explanation:
Any change in the equilibrium is studied on the basis of Le-Chatelier's principle.
This principle states that if there is any change in the variables of the reaction, the equilibrium will shift in the direction to minimize the effect.
[tex]CH_3COOH\rightleftharpoons CH_3COO^-+H^+[/tex]
Thus if [tex]CH_3COONa[/tex] is added it will dissociate to give [tex]CH_3COO^-[/tex] and [tex]Na^+[/tex]
[tex]CH_3COONa\rightarrow CH_3COO^-+Na^+[/tex]
Thus as the concentration of [tex]CH_3COO^-[/tex] increases, the equilibrium will shift in a direction where concentration of [tex]CH_3COO_-[/tex] decrease i.e. the dissociation of [tex]CH_3COOH[/tex] will be further depressed i.e the equilibrium will shift to the left.
Answer:
C
Explanation:
What is the Lewis dot structure Ch2Cl2
The red line of the hydrogen emission spectrum has a wavelength of 656.1 nm. Calculate the energy of one photon
The formula we can use here is the Plancks equation:
E = h c / ʎ
where h is Plancks constant = 6.626 × 10-34 m2 kg / s, c is speed of light = 3 x 10^8 m/s and ʎ is wavelength = 656.1 x 10^-9 m
Therefore E is:
E = (6.626 × 10-34 m2 kg / s) * (3 x 10^8 m/s) / 656.1 x 10^-9 m
E = 3.03 x 10^-19 J
The energy of one photon of the red line of the hydrogen emission spectrum can be calculated using Planck's equation and it is approximately 3.03 x 10^-19 Joules.
Explanation:The energy of a photon can be calculated using Planck's equation, E = hv, where 'E' is the energy, 'h' is Planck's constant (6.63 x 10^-34 J.s), and 'v' is the frequency. We can express frequency in terms of speed of light (c) and wavelength (λ) using the equation v = c/λ.
First, convert the wavelength from nm to meters: 656.1 nm = 656.1 x 10^-9 m. Then find the frequency, v = (3.00 x 10^8 m/s) / (656.1 x 10^-9 m) = 4.57 x 10^14 s^-1.
Next, substitute 'v' into Planck's equation to find the energy: E = (6.63 x 10^-34 J.s) x (4.57 x 10^14 s^-1) = 3.03 x 10^-19 J.
Therefore, the energy of one photon of the red line of the hydrogen emission spectrum is approximately 3.03 x 10^-19 Joules.
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The p block of the periodic table includes the elements in _______.
a. groups 3a through 8a
c. inner transition metals
b. transition metals
d. groups 1a and 2a
how many moles are in 68.4 grams of neon?
Where are the alkali metals, the alkaline earth metals, the halogens, and the noble gases located on the periodic table?
The alkali metal, the alkaline earth metals, the halogens, and the noble gases are located in the periodic table in group 1, group 2, group 17, and group 18 respectively.
What is the periodic table?The periodic table is a tabular display of chemical elements. The periodic table is a graphic formulation of the periodic law, which states that the physical and chemical properties of the chemical elements are the periodic functions of their atomic numbers.
The table is arranged in horizontal rows called periods, and the vertical columns are called groups. Elements in the same column group of the periodic table show identical chemical characteristics.
The nonmetallic character increases from left to right in a period, and from down to up across a group, and the metallic character increases in the opposite direction.
The alkali metal and the alkaline earth metals are the elements of the s-block while the halogens and the noble gases are placed in the p-block.
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Most acids ionize in solution, and most bases _____ in solution.
ionize
disperse
dissociate
vaporize
A scientist has two solutions, which she has labeled solution a and solution
b. each contains salt. she knows that solution a is 65% salt and solution b is 80% salt. she wants to obtain 120 ounces of a mixture that is 70% salt. how many ounces of each solution should she use?
To create a 120-ounce mixture that is 70% salt using Solution A (65% salt) and Solution B (80% salt), the scientist needs to mix 40 ounces of Solution A with 80 ounces of Solution B.
To solve this problem involving solution mixture, we can use the concept of the weighted average to find how many ounces of Solution A and Solution B are needed to create a new solution of desired concentration.
Let the amount of Solution A to be used be x ounces and the amount of Solution B be 120-x ounces.
Set up the equation considering that Solution A is 65% salt and Solution B is 80% salt, and we want a final mixture that is 70% salt of 120 ounces total.
The equation to be solved is 0.65x + 0.80(120-x) = 0.70(120).
Simplify and solve the equation for x.
Substitute x back into 120-x to find the amount of Solution B needed.
In this case, solving the equation gives us x = 40 ounces of Solution A and 120-x = 80 ounces of Solution B needed to achieve the 70% salt mixture.
00 ml of 0.425 m h2so4 solution is required to completely neutralize 23.9 ml of koh solution. what is the molarity of the koh solution
00 mL? I believe that you have erroneously pasted the question here.
Anyway, let us continue computing for the molarity of KOH but i will just use a variable “A” for the volume of H2SO4 solution.
The complete balanced reaction is:
H2SO4 + 2KOH --> K2SO4 + 2H2O
We see that 2 moles of KOH is needed for every mole of H2SO4. So calculate the moles of H2SO4.
moles H2SO4 = 0.245 M * (A / 1000) = 2.45x10^-4 A
So the number of moles of KOH is:
moles KOH = 2.45x10^-4 A * 2
moles KOH = 4.90x10^-4 A
So the molarity of KOH is:
Molarity KOH = 4.90x10^-4 A / (0.0239 L)
Molarity KOH = 0.0205 * A
Simply multiply 0.0205 by the correct volume of H2SO4 in ml
What is the maximum number of electrons that can occupy the 3rd electron shell
According to electronic configuration there are 18 electrons that can occupy the 3rd electron shell.
What is electronic configuration?Electronic configuration is defined as the distribution of electrons which are present in an atom or molecule in atomic or molecular orbitals.It describes how each electron moves independently in an orbital.
Knowledge of electronic configuration is necessary for understanding the structure of periodic table.It helps in understanding the chemical properties of elements.
Elements undergo chemical reactions in order to achieve stability. Main group elements obey the octet rule in their electronic configuration while the transition elements follow the 18 electron rule. Noble elements have valence shell complete in ground state and hence are said to be stable.
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How many lithium ions are present in 30.0 ml of 0.600 m li2co3 solution?
To calculate the number of lithium ions, we need to determine the number of moles of Li2CO3 and then multiply it by 2 (since there are 2 lithium ions for every 1 formula unit of Li2CO3). The number of lithium ions is 0.0360 mol.
Explanation:To determine the number of lithium ions present in the solution, we need to first calculate the number of moles of Li2CO3 using the given concentration and volume. From the formula Li2CO3, we can see that there are 2 lithium ions for every 1 formula unit of Li2CO3. Therefore, we can multiply the number of moles of Li2CO3 by 2 to calculate the number of lithium ions.
First, we need to calculate the number of moles of Li2CO3:
Moles of Li2CO3 = concentration (mol/L) × volume (L)
Moles of Li2CO3 = 0.600 mol/L × 0.0300 L = 0.0180 mol
Since there are 2 lithium ions for every 1 formula unit of Li2CO3:
Number of lithium ions = 2 × moles of Li2CO3 = 2 × 0.0180 mol = 0.0360 mol
Therefore, there are 0.0360 moles of lithium ions present in 30.0 mL of 0.600 M Li2CO3 solution.
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Classify these bonds as ionic, polar covalent, or nonpolar covalent na-f
When metals form ions, they tend to do so by 1. losing electrons and forming positive ions 2. losing electrons and forming negative ions 3. gaining electrons and forming positive ions 4. gaining electrons and forming negative ions?
Answer:
1. losing electrons and forming positive ions
Explanation:
Metals form ions by losing electrons. They do it because they have few electrons in their outermost shells. So rather than accept more electrons, it is much more feasible to lose the few electrons and achieve the octet configuration.
With this alone, we know that options 3 and 4 are incorrect.
When metals lose electrons, the type of ion formed is a positive ion because the total number of protons (positive) would be more than the total number of electrons (negative) present.
For example in Ca²⁺;
Calcium loses 2 electrons. The charge however shows +2. This is because there are 20 protons and 18 electrons in the ion now, so 20 -18 = +2
The correct option is option 1. losing electrons and forming positive ions.