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Matter Unit
Section 1
I) Matter
A.) Def: anything that …
1. Has MASS
2. Takes up space.
B.) Almost everything around us is matter.
Ex – air, table, chair, us, water, etc.
Ex. NOT MATTER – heat, light.
C.) If almost everything is matter, why doesn’t
everything look the same?
II.) Atoms
A) Def: tiny particles that are the BUILDING
BLOCKS of matter.
B) How they are arranged- why everything
looks different.
C) Properties of matter determined by
1. Types of atoms (see next slide)
2. How they attach to each other
C.) 3 basic particles of an atom
1) Neutrons
•
•
Have a NEUTRAL charge
Exist in the NUCLEUS (center/middle of atom)
2) Protons
•
•
Have a POSITIVE charge
Exist in the NUCLEUS too!
C.) Parts of Atom cont.
3) Electrons
* Have a NEGATIVE CHARGE
* Exist OUTSIDE the nucleus
* Kind of like orbits – in an “electron cloud”
*Different energy depending on how close to the
nucleus. (Think of a BEE HIVE)
< Lower Energy – closer to nucleus.
<Higher Energy – farther away from nucleus.
III) What does an atom look like?
IV.) Elements
A.) Def: substances that ~
1.) Are made up of only one type of atom.
2) Cannot be broken down into any simpler
substances by normal physical or chemical
means.
3) Periodic Table of Elements
*Familiarize yourself w/ it
*Know what those numbers mean!
V) What those “numbers mean”
(Periodic Table)
A) ATOMIC NUMBER = Number of PROTONS
* All atoms of the same element have the
same number of PROTONS
*Found above the element symbol on the
periodic table.
What is Helium’s atomic
number?
How many protons does
Helium have?
V) What those “numbers mean”
(Periodic Table) CONT.
• B) How many Electrons?
1) In a NEUTRAL atom …
Atomic No. = No. of Protons = No. of Electrons
2) Atoms can lose or gain electrons – no longer
neutral = ION (charged atom)
- More protons than electrons = Positively charged
ion.
- More electrons than protons = Negatively
charged ion.
V) What those “numbers mean”
(Periodic Table) CONT.
C) How many neutrons?
1) Atomic Mass (or Mass Number) (round – don’t
use decimals)
= # of Protons + # of Neutrons
2) Can have different number of Neutrons –
called an ISOTOPE of an element.
*Scientist uses of isotopes:
- radioactive isotopes to fight cancer
- helps determine age of rocks
VI) Practice – parts of atom
• Worksheet.
VII. Bohr’s Diagram
• One dimensional view of an atom.
• Center = nucleus w/ protons & neutrons
• Outer Shells = layered areas of electron cloud
– 1st = holds 2
– 2nd = holds 8
– 3rd = holds 18
• Why important?
SHOWS how likely atom will BOND w/ another
atom.
• Electrons in outer shell are called VALENCE
electrons.
Draw one …