Understanding Atoms, Ions, and Chemical Changes

What happens to an atom when it loses electrons?

It becomes positively charged.

What happens to an atom when it gains electrons?

It becomes negatively charged.

What is an example of an atom that gains electrons?

Oxygen, which has an electron configuration of 2,6 and gains 2 electrons.

What is a physical change?

A change that is reversible, such as water freezing.

What is a chemical change?

A change that is often irreversible and can involve color change, temperature change, or precipitation.

What is a compound?

A substance made up of two or more elements that are chemically bonded.

What is an element?

A substance made up of only one type of atom.

What is a mixture?

A combination of two or more substances that are not chemically bonded.

How is the formula Ca(OH)₂ interpreted?

Ca = 1 calcium atom, O = 2 oxygen atoms, H = 2 hydrogen atoms, totaling 5 atoms.

What is the nucleus of an atom made up of?

Protons and neutrons.

What does the atomic number represent?

The number of protons in an atom.

What does the mass number represent?

The total number of protons and neutrons in an atom.

What does the group number indicate in the periodic table?

The number of electrons in the outer shell.

What does the period number indicate in the periodic table?

The number of shells in an atom.