Chapter 17
Chemistry – is study of matter
matter- anything that has mass
and takes up space.
What is the SI unit for mass again?
I. Atomic Structure
A. Atom smallest unit of matter
(remember matter is anything that has mass and takes
up space)
Parts of atoms
a. Nucleus –
1. made up of protons (positive)
and neutrons (no charge)
2. All nucleus has positive charge
3. Heaviest part of atom
4. Very small
b. Electron cloud
1. has very small, light particles called
electrons (negative).
2. cloud is mostly empty space
3. Largest part of atom
B. Elements – material made of only one type of
atom
1. Listed in a chart – Periodic Table
2. 110 known today
II. Periodic Table
Atomic number
Chemical
symbol
Chemical name
An atom’s atomic number (# of protons)never
changes!
(it’s like its fingerprint)
An atom’s atomic mass can change because its #
of neutrons can change.
Different # of nuetrons for the same element is
called an isotope.
Sodium
23
11
Na
Protons: 11
Neutrons: 12
Electrons: 11
Rhenium
186
75
Re
Protons: 75
Neutrons: 111
Electrons: 75
Rhenium isotope
187
75
Re
Protons: 75
Neutrons: 112
Electrons: 75
1. Horizontal rows are periods
2. Vertical rows are groups
3. elements are in order of increasing atomic
numbers.
4. Group #1 is called
Alkali Metals
5. Group #2 is called
Alkaline Earth metals
6. Group#3-12 are called
Transition Metals
7. Group #17 is called
Halogen Metals
8. Group #18 is called
Noble Gas
1
2
3
4
5
6
7
Properties of Metals:
malleable, ductile, good conductors of
heat/electricity
Properties of Nonmetals: do not possess the
properites listed above for metals (often liquid or
gas in nature and may even be a very brittle solid
Metalloids- on the stairs –have some properties of
metals and some of nonmetals
- semiconductors