1. 1.4 Subatomic Particles and Isotopes Obj. 3:b,e,f; 4
Chemistry

2. Essential Questions What is atomic # and how do you determine it?
How is atomic # used to identify an element?
What is mass # and how do you determine it?
What is the difference between atomic mass and mass number?
What is an isotope?
How do you determine the number of protons, neutrons, and electrons for an isotope?

3. Atomic Number Atomic number is the number of protons.
How do you find the atomic number?
Periodic table
How do we use atomic number?
Identifies the type of element because each element has its own unique atomic number
The atomic number of a neutral atom is equal to number of electrons

4. Mass Number
Mass number is the total number of protons and neutrons in an atom (mass number = # of protons + # of neutrons)
Mass number can be used to find the number of neutrons
# of neutrons = Mass number - # of protons

5. Symbol Notation There are two way of doing symbol notation.
Mass Number (A), Atomic Number (Z), and element symbol (X)
Element name – mass number

6. Isotopes
Isotopes are atoms of the same element that have different mass numbers
Carbon – 14 and carbon – 12
The protons and electrons (if neutral) will be the same for isotopes of the same element
The neutrons and mass number will be different for isotopes of the same element

7. Isotopes (cont)
Element
Proton
Neutron
Electron 1 26 30 2 25 3 27 32 4 29
Which of the above would be isotopes of the same element?
Which would have the same mass number?
1 and 4
2 and 4

8. Atomic Mass
The atomic mass is an average mass based off of the abundance and mass of the different isotopes and is found on the periodic table.
amu – atomic mass unit
When the atomic mass is rounded to the nearest whole number that is the most common isotope of the element
Tc atomic mass is 97.9 so a mass number of 98 is the most common isotope

9. Protons, Neutrons, and Electrons
Determine the number of p, n, and e-
Cobalt – 58
Barium – 138
204Tl
227Ac
In (round the mass to the most common isotope)
Yttrium

10. Protons, Neutrons, and Electrons (cont)
Fill in the following chart
Element Shorthand
(AX)
Atomic #
Protons
Neutrons
Electrons
Mass #
159Tb
159 46 60 87
223
116 77 12 24

11. Protons, Neutrons, and Electrons (cont)
Answer Key
Element Shorthand
(AX)
Atomic #
Protons
Neutrons
Electrons
Mass #
159Tb 65 94
159
106Pd 46 60
106
223Fr 87
136
223
193Ir 77
116
193
24Mg 12 24

12. Protons, Neutrons, and Electrons (cont)
Fill in the following chart
 Element
Osmium-191
Osmium-190
Protons
Neutrons
Electrons
 Element
Protons
 57
Neutrons
 81
 83
Electrons

13. Protons, Neutrons, and Electrons (cont)
Answer Key
 Element
Osmium-191
Osmium-190
Protons
 76 76
Neutrons
115
 114
Electrons
 Element
Lanthanum-138
Lanthanum-140
Protons
 57
Neutrons
 81
 83
Electrons 57

14. Essential Questions What is atomic # and how do you determine it?
How is atomic # to the identify an element?
What is mass # and how do you determine it?
What is the difference between atomic mass and mass number?
What is an isotope?
How do you determine the number of protons, neutrons, and electrons for an isotope?

15. 1.4 Tracked Assignment
1.4 Worksheet