Almost all of the atom’s mass is located here.

• electron cloud

• protons

• nucleus

• neutrons

What unit is used to measure the mass of an atom?

• atomic weight

• atomic mass unit

• atomic grams

• atomic gram unit

What abbreviation is used to measure the mass of an atom?

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NGSS.HS-PS1-7

These two parts of an atom about the same mass of 1 amu.

• electrons and protons

• protons and nucleus

• neutrons and electrons

• protons and neutrons

The number of these identifies the type of atom.

• electrons

• protons

• neutrons

• elements

Atoms of different elements have different numbers of these.

• neutrons

• electrons

• protons

• isotopes

The number of protons in an atom’s nucleus is equal to this.

• atomic number

• mass number

This is the sum of the number of protons and neutrons in the nucleus of an atom.

• atomic number

• mass number

The mass number is equal to the number of these in the nucleus.

• electrons and neutrons

• protons and neutrons

• electrons and protons

If you know the mass number and the atomic number of an atom, you can calculate the number of these in the nucleus.