1. 5.2 The Structure of the Atom

2. The Atom Protons (p+) Electrons (e-) Neutrons (no)
The atom is made up of three subatomic particles:
Protons (p+)
Electrons (e-)
Neutrons (no)

3. The protons and neutrons are found in the nucleus at the centre of the atom.
The electrons are found “orbiting” around the nucleus in specific energy levels.

4. The Subatomic Particles
Location
Charge
Mass
Proton
nucleus +1 1
Electrons
outer shells -1
Neutrons

5. Standard Atomic Notation
Shows:
Atomic number
the number of protons in the nucleus of an atom
The atomic number identifies the atom as a particular element
Mass Number
The number of protons and neutrons in an atom

6. Uses a standard symbol to represent the element (ex
Uses a standard symbol to represent the element (ex. H for hydrogen, Li for lithium)

7. The Atom Calculating the Number of Subatomic Particles:
Atomic number = number of protons
Mass number = number of protons + number of neutrons
Number of neutrons = mass number – atomic number
Number of protons = number of electrons (neutral atom)

8. Activity 5-4, p. 189 Read the activity and complete #1-4
NOTE: for number 3, do not use Appendix A, instead use the periodic table on p. 197, the mass number is the number under the symbol, rounded. Ex. zinc 65.4 = 65.

9. Answers to Activity 5-4
1. carbon = C, hydrogen = H, nitrogen = N Rule: use the first letter (capital) of each element 2. a. Calcium = Ca, use the first two letters, first letter only capitalized. b. C cannot be used as it is already used for carbon 3. silver (argentum) = Ag, gold (aurum) = Au, copper (cuprum) = Cu, iron (ferrum) = Fe, mercury (hydrargyrum) = Hg, lead (plumbum) = Pb, tin (stannum) = Sn Identify rules…. 4. Next slide…

10. Name of Element Atomic Number Mass Number 126C Carbon 6 12 6530Zn zinc
Standard Atomic Notation
Name of Element
Atomic Number
Mass
Number
Number of Electrons
Number of Protons
Number of Neutrons
126C
Carbon 6 12
6530Zn
zinc 30 65 35
Sulfur 16
Calcium 40 20
nitrogen 7 14

11. Bohr Rutherford Diagrams
Show the quantities and locations of protons, electrons and neutrons in an atom (used for the 1st 20 elements)
Atomic Number = # of protons
# of neutrons = Mass Number – Atomic Number
# of electrons = # of protons in a neutral atom
For an atom of Helium:
Atomic # = # of protons = 2 =
= 2
# of electrons = # of protons = 2

12. Bohr-Rutherford Diagram for He
helium
2e-
# of electrons in 1st orbital (energy level)
Max = 2
2p+
2n°
# of protons (p)
# of neutrons (n)
Nucleus

13. Bohr-Rutherford Diagram for K
Potassium
1e-
# of electrons in 4th orbital (energy level) Max = 8
8e-
# of electrons in 3rd orbital (energy level) Max = 8
8e-
# of electrons in 2nd orbital (energy level) Max = 8
2e-
# of electrons in 1st orbital (energy level) Max = 2
19p+
20n°
# of protons (p)
# of neutrons (n)
Nucleus

14. Isotopes Most atoms of an element have the same number of neutrons
A few will have a different number of neutrons
Ex. Most Li atoms have 3 protons and 4 neutrons
Mass Number = 7
Some have only 3 neutrons
Mass Number = 6
Atoms that have the same number of protons but different numbers of neutrons are called isotopes.