Atoms and The Periodic Table

Column A

100

horizontal rows on the periodic table 

periods

200

an electron in the outermost energy level of an atom

valence electron

300

the subatomic particle that is electrically neutral and found in the nucleus of an atom

neutron

400

subatomic particles orbiting around the nucleus

electrons

Column B

100

the number of protons in the nucleus of an atom

atomic number

200

vertical columns also known as families 

groups 

300

particles found in the nucleus of an atom

protons and neutrons

400

the pair of particles that balance the charge of an atom

protons and electrons