Question 1

Which of the following best describes the difference between an element and a compound?

Accepted Answer

An element is a pure substance that cannot be broken down by chemical means, while a compound consists of two or more elements chemically combined.

Question 2

Which of the following elements makes up the largest percentage of the human body by mass?

Accepted Answer

Oxygen

Question 3

Which statement best explains why atoms are considered the basic units of elements?

Accepted Answer

Atoms are the smallest units that retain the chemical properties of an element.

Question 4

Which of the following correctly identifies the three subatomic particles and their charges?

Accepted Answer

Proton (positive), Neutron (neutral), Electron (negative)

Question 5

How do isotopes of the same element differ from one another?

Accepted Answer

They have different numbers of neutrons.

Question 6

Why is the concept of half-life useful for understanding radioactive isotopes?

Accepted Answer

It allows us to predict how long it will take for half of a sample to decay.

Question 7

Which of the following is a real-world application of isotopes?

Accepted Answer

Using carbon-14 to date ancient artifacts.

Question 8

What is the maximum number of electrons that can occupy the second energy level (shell) of an atom?

Accepted Answer

$$8$$

Question 9

Atoms with incomplete valence shells tend to be:

Accepted Answer

Chemically reactive

Question 10

Which of the following best describes an ionic bond?

Accepted Answer

A bond formed by transferring electrons from one atom to another.

Question 11

Which of the following atoms is most likely to form a cation?

Accepted Answer

An atom with a nearly empty valence shell

Question 12

Which of the following statements about covalent bonds is correct?

Accepted Answer

Covalent bonds involve the sharing of electrons between atoms.

Question 13

Which type of covalent bond involves the sharing of three pairs of electrons?

Accepted Answer

Triple covalent bond

Question 14

Which of the following best defines electronegativity?

Accepted Answer

The ability of an atom to attract electrons in a chemical bond.

Question 15

Which of the following molecules is most likely to have polar covalent bonds?

Accepted Answer

$$\mathrm{H_2O}$$

Question 16

Hydrogen bonds are important in biology because they:

Accepted Answer

Allow water molecules to stick together, giving water its unique properties.

Question 17

Which of the following best explains why water is a good solvent for ionic compounds?

Accepted Answer

Water molecules are polar and can surround and separate ions.

Question 18

A radioactive isotope has a half-life of 10 years. If you start with 80 grams, how much will remain after 30 years?

Accepted Answer

$$10$$ grams

Question 19

Which of the following best describes a polar covalent bond?

Accepted Answer

A bond where electrons are shared unequally, creating partial charges.

Question 20

Which of the following is an example of a molecule held together by hydrogen bonds?

Accepted Answer

The two strands of DNA in a double helix.

Matter, Elements, Atoms, and Chemical Bonding

Study Guide - Practice Questions