Vocabulary
Smallest particle of an element which retains the properties of that element
Atom
400 BC: Named Atom
Democritus
Nucleus
Why do elements in the same group have similar properties?
Same number of valence electrons
A Noble Gas with 8 valence electrons and 2 energy level in its electron cloud.
Neon
Subatomic particle located in the nucleus of an atom that has a positive charge
Proton
1803: Solid Sphere Model
John Dalton
Where most of the volume of an atom is located
Electron Cloud
What do elements in the same period have in common?
Number of energy levels
An Alkali metal with 4 energy levels.
Potassium
Subatomic particle located in the nucleus of an atom that has a neutral charge
Neutron
1869: Arranged periodic table by mass
Mendeleev
Which number tells you the amount of protons?
Atomic Number
What is the group name for the most reactive metals?
Alkali metals
Has five valence electrons and is in period 3.
Phosphorus
Subatomic particle located in the electron cloud surrounding the nucleus that has a negative charge.
Electron
1904: Plum Pudding Model
JJ Thomson
Which number tells you the amount of protons and neutrons?
Mass Number
What is the group name for the most reactive nonmetals?
Halogens
The only metalloid in period 3.
Silicon
e- in the outermost energy level of the electron cloud
Valence Electrons
1913: Periodic Table by Atomic Number
Henry Moseley
What is different about two isotopes of the same element?
Neutrons
The group that is nonreactive.
Noble Gases
The first element in Group 13
Boron