# Chem

## Chem

﻿The amount of protons is called the element's Atomic Number (listed above the element on the periodic table. )

The Mass Number is the number of protons plus neutrons.

An atom of carbon can have 6, 7, or 8 neutrons. It doesn't matter, we will still call it 'carbon.'
If a carbon atom has 6 neutrons, its Mass Number is 12. (6 protons + 6 neutrons)
If a carbon atom has 7 neutrons, its Mass Number is 13. (6 protons + 7 neutrons)
You try:
If a nitrogen atom has 8 neutrons, its Mass Number is ______. (7 protons + 8 neutrons)

If a nitrogen atom has 10 neutrons, its Mass Number is ______.

If a sulfur atom has 16 neutrons, its Mass Number is _______.

If a gold atom has 120 neutrons, its Mass Number is ______. (79 protons + 120 neutrons)

Atoms that have the same amount of protons, but different amounts of neutrons are called isotopes. Isotopes are written this way:

Carbon-1 , Carbon-13, Carbon-14 Or: 12C 13C 14C

How many neutrons does Oxygen-18 have? (also written 18O)
Answer: protons + neutrons = 18
protons = 8 (from periodic table)
18 - 8 = 10 neutrons

How many neutrons do these isotopes have?
Sulfur-36 ____ Calcium-40 ____ Phosphorus-32 ____

90Zr ____ 69Zn ____ 56Fe ____

The number of electrons equals the number of protons (in a neutral atom).

How many protons, neutrons and electrons do these atoms (isotopes) have?

Aluminum-26: protons________ neutrons___________ electrons___________

Bromine-81: protons________ neutrons___________ electrons___________

Oxygen-16: protons________ neutrons___________ electrons___________

Silver 107 (Ag-107) protons________ neutrons___________ electrons___________

Silver 109 (Ag-109) protons________ neutrons___________ electrons___________