Q: Copper has two naturally occurring isotopes: $^{63}\mathrm{Cu}$ (69.17%, mass = 62.93 amu) and $^{65}\mathrm{Cu}$ (30.83%, mass = 64.93 amu). What is the atomic mass of copper?

$(0.6917 \times 62.93) + (0.3083 \times 64.93) = 63.55$ amu

Question 1

Which statement best describes Dalton’s atomic theory as it relates to chemical reactions?

Accepted Answer

Atoms are rearranged to form new combinations in a chemical reaction.

Question 2

A neutral atom of phosphorus has an atomic number of 15 and a mass number of 31. How many neutrons does it contain?

Accepted Answer

$31 - 15 = 16$ neutrons

Question 3

Which subatomic particle has the smallest mass?

Accepted Answer

Electron

Question 4

Copper has two naturally occurring isotopes: $^{63}\mathrm{Cu}$ (69.17%, mass = 62.93 amu) and $^{65}\mathrm{Cu}$ (30.83%, mass = 64.93 amu). What is the atomic mass of copper?

Accepted Answer

$(0.6917 	imes 62.93) + (0.3083 	imes 64.93) = 63.55$ amu

Question 5

Which element is a metalloid and has properties intermediate between metals and nonmetals?

Accepted Answer

Silicon (Si)

Question 6

What is the electron-dot symbol for chlorine (Cl), a group 7A element?

Accepted Answer

Cl with 7 dots around it

Question 7

Which of the following statements about isotopes is correct?

Accepted Answer

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

Question 8

A cobalt atom used in cancer treatments has $Z = 27$ and $A = 60$. How many electrons does a neutral atom of this isotope have?

Accepted Answer

$27$ electrons

Question 9

Which group on the periodic table contains the noble gases?

Accepted Answer

Group 8A (or 18)

Question 10

Which property is NOT characteristic of metals?

Accepted Answer

Brittle and dull

Question 11

How many valence electrons does magnesium (Mg) have?

Accepted Answer

2

Question 12

Which of the following elements is most likely to be found as a colorful and corrosive nonmetal?

Accepted Answer

Bromine (Br)

Question 13

What is the charge of a neutron?

Accepted Answer

0 (neutral)

Question 14

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

Accepted Answer

They have the same number of valence electrons.

Question 15

If an atom has 17 protons, 18 neutrons, and 17 electrons, what is its atomic number and mass number?

Accepted Answer

Atomic number $= 17$, Mass number $= 35$

Question 16

Which orbital type can hold a maximum of 2 electrons?

Accepted Answer

Any single orbital (s or p)

Question 17

Which element is a liquid metal at room temperature?

Accepted Answer

Mercury (Hg)

Question 18

Which of the following is the correct electron-dot symbol for neon (Ne)?

Accepted Answer

Ne with 8 dots around it

Question 19

Which of the following is a correct statement about the atomic number ($Z$) of an element?

Accepted Answer

It is equal to the number of protons in the atom.

Question 20

A patient receives a dose of carbon-14 for a medical test. Which statement is true about carbon-14 compared to carbon-12?

Accepted Answer

Carbon-14 has more neutrons than carbon-12.

Atoms and the Periodic Table: Structure, Properties, and Classification

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