Q: Calculate the average atomic mass of chlorine if $$^{35}\mathrm{Cl}$$ has a mass of 34.969 amu and an abundance of 75.78%, and $$^{37}\mathrm{Cl}$$ has a mass of 36.966 amu and an abundance of 24.22%.

$$(0.7578 \times 34.969) + (0.2422 \times 36.966) = 35.45$$ amu

Q: A sample contains 98.93% $$^{12}\mathrm{C} (12 $$amu) and 1.07% $$^{13}\mathrm{C} (13.00335 $$amu). What is the atomic weight of carbon?

$$(0.9893 \times 12) + (0.0107 \times 13.00335) = 12.01$$ amu

Q: What is the value of 1 atomic mass unit (amu) in grams?

$$1 \mathrm{amu} = 1.66054 \times 10$$^{-24}$$ \mathrm{g}$$

Question 1

Which scientist is credited with discovering the law of conservation of mass, and what does this law state?

Accepted Answer

Antoine Lavoisier; it states that the total mass of substances present at the end of a chemical process is the same as the mass before the process.

Question 2

A neutral atom of $$^{138}\mathrm{Ba}$$ has how many protons, neutrons, and electrons?

Accepted Answer

56 protons, 82 neutrons, 56 electrons

Question 3

Which law states that if two elements form more than one compound, the masses of one element that combine with a fixed mass of the other are in the ratio of small whole numbers?

Accepted Answer

Law of multiple proportions

Question 4

What is the atomic number ($$Z) $$and mass number ($$A) $$for $$^{197}\mathrm{Au}$$?

Accepted Answer

$$Z = 79$$, $$A = 197$$

Question 5

Which statement about isotopes is correct?

Accepted Answer

Isotopes have different numbers of neutrons but the same number of protons.

Question 6

Calculate the average atomic mass of chlorine if $$^{35}\mathrm{Cl}$$ has a mass of 34.969 amu and an abundance of 75.78%, and $$^{37}\mathrm{Cl}$$ has a mass of 36.966 amu and an abundance of 24.22%.

Accepted Answer

$$(0.7578 	imes 34.969) + (0.2422 	imes 36.966) = 35.45$$ amu

Question 7

Which subatomic particle has a mass that is approximately 1/1840 that of a proton?

Accepted Answer

Electron

Question 8

What is the formula to calculate the number of neutrons ($$n^0) in an $$atom?

Accepted Answer

$$n^0 = A - Z$

Question 9

Which element would you expect to have chemical properties most similar to sodium (Na)?

Accepted Answer

Potassium (K)

Question 10

Which group in the periodic table contains the noble gases?

Accepted Answer

Group 8A

Question 11

A sample contains 98.93% $$^{12}\mathrm{C} (12 $$amu) and 1.07% $$^{13}\mathrm{C} (13.00335 $$amu). What is the atomic weight of carbon?

Accepted Answer

$$(0.9893 	imes 12) + (0.0107 	imes 13.00335) = 12.01$$ amu

Question 12

Which of the following statements about the periodic table is correct?

Accepted Answer

Elements in the same group have similar chemical properties.

Question 13

Which of the following is NOT a postulate of Dalton’s atomic theory?

Accepted Answer

Atoms of the same element can have different numbers of neutrons.

Question 14

Which element is a metalloid according to the periodic table organization?

Accepted Answer

Silicon (Si)

Question 15

If a neutral atom has 28 protons and 31 neutrons, what is its atomic number and mass number?

Accepted Answer

Atomic number = 28, Mass number = 59

Question 16

Which of the following best describes the location of electrons in the atom according to the current model?

Accepted Answer

Electrons are located in a cloud outside the nucleus.

Question 17

What is the value of 1 atomic mass unit (amu) in grams?

Accepted Answer

$$1 \mathrm{amu} = 1.66054 	imes 10$$^{-24}$$ \mathrm{g}$$

Question 18

Which of the following elements is a nonmetal?

Accepted Answer

Oxygen (O)

Question 19

Which property is shared by elements in the same group of the periodic table?

Accepted Answer

They have similar chemical properties.

Atoms, Molecules, and Ions: Foundations of Atomic Theory and the Periodic Table

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