TEKS 8.5B
I should know/be able to: Identify that protons determine an element's identity
valence electrons determine its chemical properties, including reactivity
and valence electrons determine its chemical properties, including reactivity.
Protons:
positively charged subatomic particle; 1 amu; located in nucleus; determine identity of the
element; contribute to the mass of the atom; DO NOT CHANGE NUMBER; are atomic number
Valence Electrons: outermost electrons (farthest from nucleus); determine reactivity
Protons are the Identity of Atoms
Each element has a unique number of
protons in all of its atoms. The atomic
numbers of an element is the number
of protons in each of its atoms. To
identify which element a model of an
atom is depicting, count the number
of protons in the nucleus and find the
element on the periodic table with
that atomic numbers.
Ion- an atom with a charge
Atomic Number- the number of
protons; used to organize the
periodic table
Reactivity is the rate at which a chemical substance
tends to undergo a chemical reaction (bonds with
other atoms)
-Atoms are most stable, and thus will not react with
other atoms, when their outer (valence) electron
orbital is completely full. For the period 1 elements,
this is two electrons; for other elements, this is eight
electrons. All of the group 18 elements, known as the
noble gases, have a full valence electron orbital, and
thus are completely non-reactive.
-Atoms that only have one valence electron (group 1
elements) are very reactive, because they need only
lose that one electron in a reaction to expose an inner
full electron orbital and become stable (hydrogen
excepted).
-Atoms that have 7 valence electrons (group 17
elements) are very reactive, because they need only
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gain one electron in a reaction
to complete their
outer valence electron orbital.
Valence Electrons
In the Bohr Model of the atom,
electrons fill different electron
orbitals (also known as electron
shells or energy levels) from the
inside out. The first orbital can only
hold 2 electrons. The second orbital
can hold 8 electrons, and the third
can hold up to 18, but the outermost
orbital can never have more than 8
electrons. Only these outermost
electrons, known as valence
electrons can interact with other
atoms in chemical reactions.
Group/Family
Number
Valence Electrons
1 2 13 14 15 16 17 18
1 2 3 4
5
6
7
8
Electron- negatively charged subatomic
particle located outside the nucleus
Group/Family Columns on Periodic Table
 Share same # of valence electrons
 Share similar chemical & physical
properties
Element
Number
of
Protons
8
Total
Electrons
Valence
Electrons
Number of
Neutrons
Atomic
Mass
8
6
8
16
Oxygen
Metal, NonMetal, or
Metalloid?
Lithium
Atomic #: ___
Protons: ___
Electrons:___
Valence: ___
Neutrons: __
Coming Soon!!
6
6
4
6
12
19
19
1
20
39
Carbon
Potassium
3
3
1
4
7
5
5
3
6
11
10
10
8
10
20
18
18
8
18
36
1
1
1
0
1
79
79
118
197
12
12
2
12
224
14
4
14
28
# Electrons to fill 1st Level: ___________
17
7
18# Electrons to35
fill 2nd Level: ___________
2
2
2 # Electrons to4fill 3rd Level: ____________
Lithium
Boron
Neon
Atomic #: ___
Protons: ___
Electrons:___
Valence: ___
Neutrons: __
Neon
Argon
Hydrogen
Gold
Magnesium
14
Diagram of Boron Atom
Silicon
17
Chorine
2
Helium
Magnesium
Atomic #: ___
Protons: ___
Electrons:___
Valence: ___
Neutrons: __
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