Chapter 2: Atoms & Chemical Bonds

What is matter?

Matter is anything that takes up space and has mass.

What elements make up 96% of living matter?

Carbon (C), Oxygen (O), Hydrogen (H), and Nitrogen (N).

What is an atom?

The smallest unit of matter that retains the properties of an element.

Define protons, neutrons, and electrons.

Protons are positively charged and found in the nucleus; neutrons have no charge and are also found in the nucleus; electrons are negatively charged and orbit around the nucleus.

What is the atomic number?

The number of protons in an element’s nucleus.

What is the mass number?

The sum of protons and neutrons in the nucleus.

What are isotopes?

Isotopes are atoms of the same element that differ in the number of neutrons.

What is a radioactive isotope?

An isotope that decays spontaneously, giving off energy.

What are valence electrons?

Electrons in the outermost shell of an atom.

What is a compound?

A substance composed of two or more elements in a fixed ratio.

What is a covalent bond?

The sharing of a pair of valence electrons by two atoms.

Define polar covalent bond.

A bond where electrons are unequally shared between atoms.

What is an ionic bond?

A bond formed when an atom transfers electrons to another atom, creating charged ions.

What is a cation?

A positively charged ion that loses electrons.

What is an anion?

A negatively charged ion that gains electrons.