The three

SUBATOMIC PARTICLES

areProton

Electron

Neutron

PROTON

Symbol charge

location

Mass

in the nucleus

same as neutron

+1 p+

ELECTRON

Symbol charge

Location

Mass

e- -1

tiny; 1/2000 of a proton

outside the nucleus

Force inside atoms

• Electrons are bound to the nucleus by the attractive force between electrons (-) and protons (+).

NEUTRON

Symbol n charge 0

Location in the nucleus

Mass same as proton

Element Card

82

PbLead

207.2

Atomic Number

Element Symbol

Element Name

Atomic Mass

ATOMIC NUMBER – equals the number of protons in an atom of an element

82

PbLead

207.2

Atomic Number

Element Card

ATOMIC NUMBER – equals the number of protons in an atom of an element

Element Atomic Number

Number of Protons

Carbon 6

Calcium 20

Silver 47

BALANCING CHARGE* the +1 charge of a proton exactly equals the -1 charge of an electron

* all atoms are electrically neutral * in an atom the number of

protons equals the number of electrons

Element Atomic Number

Number of Protons

Number of Electrons

Oxygen 8

Copper 29

Gold 79

MASS NUMBER – the sum of the protons and neutrons in the nucleus

Atomic Mass

82

PbLead

207.2

• The number of neutrons = mass number –

atomic number

Mass Number

Number of Protons(Atomic Number)

Number of Neutrons

19 206 6

27 1366 30

• ISOTOPES – atoms of the same element have different numbers of neutrons

Isotope Mass Number

Atomic Number

Number of Protons

Number of Neutrons

Oxygen - 16 8

Oxygen - 17

Oxygen - 18

To summarize isotopes:

They are atoms of the same element

They have the same number of protons .

They have different number of neutrons .

They have different mass numbers.

They have the same chemical and physical properties.