Atomic number and atomic mass explanation with examples

1. Atomic Structure
Atomic Number and Atomic Mass

2. Structure of the Atom
• Atom – smallest particle of an element that can exist
alone
– Two regions of an atom
• Nucleus
– Center of atom
– Protons and neutrons
• Electron “cloud”
– Area surrounding nucleus
containing electrons

3. Structure of the Atom
• Proton – Positive charge (+), 1 atomic mass unit (amu);
found in the nucleus
– amu -Approximate mass of a proton or a neutron
• Neutron – Neutral charge (0), 1 amu; found in the
nucleus
• Electron – Negative charge (-), mass is VERY small

4. • Atomic Number
– Number of protons in nucleus
– The number of protons determines identity of the element!!
• Mass Number (Atomic Mass)
– Number of protons + neutrons
– Units are g/mol

5. – Nuclear Symbol Notation

6. Find out the Atomic number and Atomic
Mass of Sulfur using the given Atomic
model.

7. Atomic Number= 16
(Since it has 16 protons in the Nucleus)
Atomic Number = 16+16 = 32
( Since 16 proton and 16 neutrons are
present in the nucleus)
16 Electrons are present in shells of
Sulfur

8. Let complete the given
information
Aluminum (Al)
Protons = 13
Electrons =
Neutrons = 14
Atomic Number =
Atomic Mass =
Let complete the given
information
Aluminum (Al)
Protons = 13
Electrons = 13
Neutrons = 14
Atomic Number = 13
Atomic Mass = 13+14= 27

9. • Nuclear Symbol notation (no
periodic table)
– Protons =
– Electrons =
– Neutrons =
– Atomic Number =
– Atomic Mass =
A
g
108
47

10. • Nuclear Symbol notation (no
periodic table)
– Protons = 47
– Electrons = 47
– Neutrons = 108-47=61
– Atomic Number = 47
– Atomic Mass = 108
A
g
108
47

11. • use the periodic table
– Protons =
– Electrons =
– Neutrons =
– Atomic Number =
– Atomic Mass =
Uranium-235

12. • use the periodic table
– Protons = 92
– Electrons = 92
– Neutrons = 235-92= 143
– Atomic Number = 92
– Atomic Mass = 235
Uranium-235

13. Use the periodic table
– Charge =
– Protons =
– Electrons =
– Neutrons =
– Atomic Number =
– Atomic Mass =
K
39 1+

14. Use the periodic table
– Charge = +1
– Protons = 19
– Electrons = 18
– Neutrons = 39-19=20
– Atomic Number = 19
– Atomic Mass = 39
K
39 1+