1. Atomic Structure Nucleons Atomic Number
Particles in the nucleus of atom
Proton
Neutron
Atomic Number
Number of protons in the atom of an element
Neutral atom
# of protons (+) = # of electrons (-)
Episode 302

2. Isotope
Atoms of an element the have a different number of neutrons (different mass)
Isotopes of Hydrogen
Hydrogen – 1
1 proton and 0 neutrons
Hydrogen – 2
1 proton and 1 neutron
Hydrogen – 3
1 proton and 2 neutrons
Mass Number
Total number in protons and neutrons in an atom
Episode 302

3. Ne C 14 20 6 10 Examples Atomic Mass Carbon – 14 Neon – 20
Weighted average of the masses of all the element’s isotopes 14 20 Ne C 6 10
Particle
Charge
Mass
Location
Proton
Neutron
Electron +1
1 amu
nucleus
neutral
1 amu
nucleus -1
0 amu
e- cloud
Episode 302

4. Subatomic Particles 3 protons 3 electrons ? neutrons
# of protons = atomic number # of electrons = atomic number # of neutrons = mass number – atomic number
3 protons
Round the average atomic mass b/c its mass is closest to the most abundant isotope.
3 electrons
? neutrons
7 – 3 = 4 neutrons
26 protons
26 electrons
56 – 26 = 30 neutrons
Episode 302

5. Carbon – 14 Oxygen – 17 Find atomic number Mass number – atomic number
6 protons
6 electrons
Mass number – atomic number
14 – 6 = 8 neutrons
Oxygen – 17
8 protons
8 electrons
17 – 8 = 9 neutrons
Episode 302

6. N 15 7 7 protons 7 electrons 15 – 7 = 8 neutrons 2 protons 2 electrons
Episode 302