Biology
Unit 2
Chapter 2
Notes #1
Matter
Pure Substances
(can be represented
by a chemical
Formula)
Elements
Compounds
Mixtures
(can be separated
By physical means)
Homogenous
Heterogeneous
Solution
Suspension
Colloid
Matter- Pure Substances
 All
samples of matter are composed of
atoms…

The smallest particles possessing the properties of
an element
• Fundamental chemical substances from which all other
substances are made
• The combination of protons, neutrons and electrons
What is an Atom?

Atom: Smallest unit
of all matter
 2 Main Parts:

Nucleus • 1) Proton (+)
• 2) Neutron (0)

Electron Cloud
• 3) Electron (-)
 The
mass of an
atom is in the
nucleus
 Electron mass is
negligible
Periodic Table
 Elements
(substance made of only 1 type
of atom) are identified on the Periodic
Table
 Periods


7 Horizontal Rows (across)
By increasing atomic number
 Groups/Families


Columns (up and down)
Have elements with similar properties
Periodic Table
 All
atoms are composed of smaller
particles including equal numbers of
protons (+) and electrons (-)
 Atomic Number = # of protons

Distinguishes one element from another
 Elements
are in sequence by atomic
number
 The table also reflects the arrangement of
electrons....
Reading the Periodic Table

Atomic Number: Number
of protons the atom
contains


Usually # of electrons also
Atomic Mass: Combined
# of protons and neutrons
inside the nucleus

Electrons too small to affect
mass
Reading the Periodic Table

Atomic Number: Number  How many protons,
of protons the atom
electrons, and neutrons
contains
does Carbon contain?


Usually # of electrons also
Atomic Mass: Combined
# of protons and neutrons
inside the nucleus

Electrons too small to affect
mass
Protons = ______
Electrons = ______
Neutrons = ______
Reading the Periodic Table

Atomic Number: Number  How many protons,
of protons the atom
electrons, and neutrons
contains
does Carbon contain?


Usually # of electrons also
Atomic Mass: Combined
# of protons and neutrons
inside the nucleus

Electrons too small to affect
mass
Protons = ______
Electrons = ______
Neutrons = ______
Reading the Periodic Table
Protons
6 + Neutrons
+ Neutrons
= 12
= 12

Atomic Number: Number  How many protons,
of protons the atom
electrons, and neutrons
contains
does Carbon contain?


Usually # of electrons also
Atomic Mass: Combined
# of protons and neutrons
inside the nucleus

Electrons too small to affect
mass
Protons = ______
Electrons = ______
Neutrons = ______
What’s the:
A)
Atomic number of
Beryllium?
4
Atomic number =
Atomic mass =
Atomic number =
protons usually
amount of protons
amount of protons
same as electrons
+ neutrons
B) Atomic mass of Beryllium?
9
C) How many protons?
4
D) How many electrons?
4
E) How many neutrons?
5
How atoms differ….

For now, electrons and protons will be equal
 # of neutrons can be different


Atoms with the same number of protons and different
numbers of neutrons are called isotopes
Mass Number = #protons + #neutrons
#p+
#n0
#e-
Hydrogen-1
1
0
1
Hydrogen-2
1
1
1
Hydrogen-3
1
2
1
Isotopes
How atoms differ
Isotope Name
Mass
Number
Atomic
Number
Number
of
Protons
Number
of
Electrons
Number
of
Neutrons
16
19
Carbon -12
Potassium-40
19
208
82