Name _____________________
Date __________________
ATOMIC THEORY
VOCABULARY
Word
Atom
Definition
- The smallest building block of matter
Nucleus
- Cluster of protons and neutrons that
make up the core of an atom
- Center of the atom
Proton
-
Neutron
- A neutrally charged particle found in
the nucleus
- Number of neutrons = atomic mass –
atomic number
- Has mass
Electron
- A negatively charged particle found
circling the nucleus
- Moves around the nucleus in an area
called an orbital (shell)
- Does not have mass
Element
- A substance made up of only one type
of atom
Chemical symbol
- An abbreviation for the element’s name
A postively charged particle found in
the nucleus
- Atomic number = number of protons
- Has mass
Word
Atomic number
Definition
- Number of protons in the nucleus
Atomic mass
- The number of protons and neutrons in
the nucleus
- Total mass of the atom
Compound
- Groups of two or more elements
combined
Formula
- Shows the numbers and types of atoms
in a molecule
- Scientific recipe for one molecule
Period Table of
Elements
- A catalog of all the known elements
organized in order of increasing atomic
number and grouped according to
similar chemical properties
Atom vs. Molecule
Atom
Cu
Ne
Molecule
N2
CO (Carbon and Oxygen)
P4
HF
Element vs. Compound
Element
P4
Br2
N2
Cu
Ne
ATOMIC
PART
PROTON
NEUTRON
ELECTRON
Compound
C 2H 6
NaOH
K2SO4
HgS
HF
MASS
CHARGE
Yes
Positive
No
X
X
WHERE FOUND
Negative
Neutral
X
X
X
X
Inside
Nucleus
Outside
Nucleus
X
X
X
Make sure you can look up the name of an element on the periodic table and give its
symbol. Also, make sure you can look up a symbol on the periodic table and give its
name.