Science 8 Study Guide: Atoms & Elements
Test: THURSDAY NOV. 20
What are Atoms?
- An atom is a very small particle that makes up all matter (Solids, liquids, and
gases)
- Atoms of a given element are alike; atoms of different elements are different
What are the parts of an atom?
- Protons are positive and found within the Nucleus
- Neutrons are neutral (no charge) and are located within the nucleus
- Electrons are negative and orbit outside the nucleus
How are electrons arranged in an atom?
-Electrons are arranged into energy levels, or shells
- The 1st energy level (“K” shell) can hold up to 2 electrons
- The 2nd energy level (“L” shell) can hold up to 8 electrons
- The 3rd energy level (“M” shell) can hold up to 18 electrons, BUT the outermost
shell, known as the Valence shell, can only hold up to 8 electrons. Exception: The
“K” shell can only hold 1 or 2 electrons!
2 Electron Diagrams:
Bohr’s Model (Shows ALL electrons):
Lewis Dot Structure (Shows only
OUTER Shell Electrons) Hint:
Look at Element’s Group #
What is the difference between atomic mass and atomic number?
-Each proton and neutron has a mass of 1 a.m.u (atomic mass unit)
- Protons + Neutrons= Atomic Mass
- The atomic number tells us the number of protons (and electrons)
- Atoms of the same kind of the same kind of matter that different numbers of
neutrons are called isotopes
What are elements?
-An element is matter that has only one kind of atom and cannot be broken down
any smaller
- The names of elements can be written in symbol form.
 The symbol always begins with a Capital letter
 If there is a 2nd or 3rd letter it is lowercase
What is the periodic table of elements?
-Each ROW across is called a period
-Each column is called a group, or family. (More closely related, similar properties
& react in similar ways)
-Elements are divided into two types- metals and nonmetals
 Metals are on the left side, Nonmetals are on the right side,
Metalloids are touching the staircase
What are the properties of metals and Nonmetals?
- Metals are solid at room temperature
o Nonmetals are liquids or gases
- Metals are silver-gray, except for gold and copper
- Metals are good conductors of heat and electricity
o Nonmetals are good insulators
- Metals have a shiny look called metallic luster
o Nonmetals are dull
- Metals are malleable; they can be hammered without breaking
o Nonmetals will break