Atoms

Page 1

Parts of an atom:

NUCLEUS:

Protons - positive charge

Neutrons - no charge

Protons + neutrons = atomic mass

ELECTRON CLOUD:

Electrons - negative charge

- the number of protons and electrons MUST be the same in a neutral atom

Page 2

Isotopes

- different number of neutrons

- the number of protons and electrons stays the same

- AVERAGE ATOMIC MASS = the average mass of the element's isotopes

- the average atomic mass is weighted according to the abundance of each isotope

Page 3

Ions

- different number of protons and neutrons

- either positively/negatively charged

- ex: Na2

Page 4

Radioactivity

- made up of particles

ALPHA DECAY

unstable nucleus

two fewer protons and two fewer neutrons = alpha particle

BETA DECAY

unstable nucleus

one neutron changes into a proton

one fewer electron = beta particle

GAMMA RAYS

- no change in element