Symbols for Isotopes
Isotopic Symbol
• X = element symbol
• A = mass number
A
Z
X
C
Typical Isotopyic Symbol
• [# of protons (p) + # neutrons (n)]
• Z = atomic number [# of protons]
• N = # of neutrons
• A-Z=N
• C = Overall Charge
19
9
F
Flourine Isotopyic Symbol
Important Equations
• How to find protons:
• Atomic Number = # of Protons
• Mass Number: Weight of an Atom = Protons + Neutrons
• (P + N = MN)
• How to find neutrons:
• Mass Number – Atomic Number = Neutrons
• (N = MN – P)
• How to find Electrons:
• Protons + Electrons = Net Charge of atom
• P+ + e- = Net Charge
• Electrons are always negative
Mass Number Equation
• A = Mass Number
• Z = Atomic Number
•
A - Z = N (Number of Neutrons)
• If you subtract Z from A then you find the number of
neutrons in an atom
Build an isotopic symbol for
an atom that contains:
19 electrons
19 protons and
20 neutrons
Build an isotopic symbol for:
Nitrogen
with 8 neutrons
Build an isotopic symbol for:
bromine atom with a mass number of 80
19
9
F
• Proton:
• Neutron:
• Electron:
Find the number of protons,
neutrons and electrons in
this isotopic symbol.
22
10
Ne
• Proton:
• Neutron:
• Electron:
Find the number of protons,
neutrons and electrons in
this isotopic symbol.
30
14
Si
-
• Proton:
• Neutron:
• Electron:
Find the number of protons,
neutrons and electrons in
this isotopic symbol.
23
11
Na
+ • Proton:
• Neutron:
• Electron:
Find the number of protons,
neutrons and electrons in
this isotopic symbol.
9
4
Be
-5
• Proton:
• Neutron:
• Electron:
Find the number of protons,
neutrons and electrons in
this isotopic symbol.
11
5
B
-3
• Proton:
• Neutron:
• Electron:
Find the number of protons,
neutrons and electrons in
this isotopic symbol.
Mass Number Equation Practice
14
6
18
8
C
O
18 – 8 = 10
8 ≠ 10
N
15 – 7 = 8
7≠8
15
7
14 – 6 = 8
6≠8
3
1
Neutrons
Isotope
12
6
Neutrons
Isotope
8
3
Neutrons
Isotope
A–Z=N
H
C
Li
3–1=2
1≠2
Neutrons
Isotope
12 – 6 = 6
6=6
Neutrons
balanced Atom
8–3=5
3≠5
Neutrons
Isotope
1.• What is the atomic number, mass number and symbol
for the element that has 45 protons and 58 neutrons?
2.
3.
4.
Give the complete symbols for ions with the following
numbers of subatomic particles:
5.• 15 protons, 16 neutrons, and 18 electrons _________
6.• 56 protons, 82 neutrons, and 54 electrons _________
7.• 13 protons, 14 neutrons, and 10 electrons _________
Practice Quiz Study Guide
1.
Atomic # = Number of Protons
2.
Mass Number = Proton + Neutrons
3.
How to find Neutrons: Mass Number – Atomic Number
4.
How to find net charge: P + E = Net Charge
Mass Number
5.
How to Write an Isotypic Symbol:
Atomic Number
A
Z
X
C
Net charge
Element Symbol
Typical Isotopyic Symbol
6.
Mass Number and Atomic mass:
ARE NOT THE SAME THING
Carbon
6
Mass Number 14
6
C
12.011
Atomic Mass
Practice Quiz
1.
What is the atomic number?
2. What is the mass number?
3.
How many neutrons are there?
4. How many electrons?
5. What is the atomic mass?
Nitrogen
-3
18
7
N
14.00674