Q: Calculate the atomic mass of chlorine given the following data: $$^{35}Cl ($$mass = 34.969 amu, abundance = 75.77%), $$^{37}Cl ($$mass = 36.966 amu, abundance = 24.23%).

$$(34.969 \times 0.7577) + (36.966 \times 0.2423) = 35.45$$ amu

Q: A sample of silicon contains three isotopes: $$^{28}Si (92.21$$%), $$^{29}Si (4.69$$%), and $$^{30}Si (3.10$$%). Which equation correctly calculates the atomic mass of silicon?

$$(27.9769 \times 0.9221) + (28.9765 \times 0.0469) + (29.9737 \times 0.0310)$$

Question 1

Which statement best describes Dalton's atomic theory as it relates to the Law of Conservation of Matter?

Accepted Answer

Atoms are indivisible and chemical reactions only rearrange them, not create or destroy them.

Question 2

Which experiment provided evidence that atoms contain smaller, negatively charged particles?

Accepted Answer

Cathode ray tube experiment

Question 3

What was the major conclusion from Rutherford's gold foil experiment?

Accepted Answer

Most of the atom is empty space with a dense, positively charged nucleus.

Question 4

Which subatomic particle is responsible for the chemical identity of an element?

Accepted Answer

Proton

Question 5

An isotope of carbon has 6 protons and 8 neutrons. What are its atomic number $$(Z)$$ and mass number $$(A)$$?

Accepted Answer

$$Z = 6, \ A = 14$$

Question 6

Which of the following best explains why elements in the same group of the periodic table have similar chemical properties?

Accepted Answer

They have the same number of valence electrons.

Question 7

A neutral atom of sodium $$(Na)$$ has an atomic number of 11 and a mass number of 23. How many protons, neutrons, and electrons does it have?

Accepted Answer

11 protons, 12 neutrons, 11 electrons

Question 8

Which group on the periodic table is known as the noble gases, and what is a key property of these elements?

Accepted Answer

Group 8A; chemically inert under standard conditions

Question 9

Which of the following statements about isotopes is correct?

Accepted Answer

Isotopes of an element have different numbers of neutrons.

Question 10

Calculate the atomic mass of chlorine given the following data: $$^{35}Cl ($$mass = 34.969 amu, abundance = 75.77%), $$^{37}Cl ($$mass = 36.966 amu, abundance = 24.23%).

Accepted Answer

$$(34.969 	imes 0.7577) + (36.966 	imes 0.2423) = 35.45$$ amu

Question 11

Which property increases as you move from left to right across a period in the periodic table?

Accepted Answer

Ionization energy

Question 12

Which of the following best describes a metalloid?

Accepted Answer

An element with properties intermediate between metals and nonmetals

Question 13

A sample of silicon contains three isotopes: $$^{28}Si (92.21$$%), $$^{29}Si (4.69$$%), and $$^{30}Si (3.10$$%). Which equation correctly calculates the atomic mass of silicon?

Accepted Answer

$$(27.9769 	imes 0.9221) + (28.9765 	imes 0.0469) + (29.9737 	imes 0.0310)$$

Question 14

Which of the following is a qualitative observation?

Accepted Answer

Copper is a reddish-brown solid.

Question 15

Which element is defined by the atomic number $$Z = 17$$?

Accepted Answer

Chlorine

Question 16

Which of the following best explains why metals are good conductors of electricity?

Accepted Answer

They have loosely held valence electrons that can move freely.

Question 17

Which group contains the most reactive nonmetals, and what is their common name?

Accepted Answer

Group 7A; halogens

Question 18

If an atom has 15 protons, 16 neutrons, and 15 electrons, what is its chemical symbol and mass number?

Accepted Answer

P, 31

Question 19

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

Accepted Answer

Elements in the same group have similar chemical properties.

Atoms and Elements: Foundations of Atomic Theory and the Periodic Table

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