C2.2 Atomic structure and the Periodic Table

What is an atom?

• The smallest particle that can exist which are the building blocks of all matter

What is a neutral atom?

• An atom that has no net electric charge because it has the same amount of protons and electrons

  • All elements in the periodic table are neutral atoms

Describe the structure of an atom

• Made up of protons, electrons and neutrons

• Protons and neutrons are located at the center of the atom called the nucleus

  • The nucleus has a positive charge

• Electrons move around the nucleus in orbital paths called shells

What is the location, relative mass and charge of the subatomic particles?

• Protons: 

  • Location: nucleus

  • Relative mass: 1

  • Charge: 1+

• Neutrons:

  • Location: nucleus

  • Relative mass: 1

  • Charge: 0

• Electrons:

  • Location: shells

  • Relative mass: 0 (negligible mass)

  • Charge: 1-

What is proton/atomic number?

• The atomic number is the total number of protons in the nucleus

  • In neutral atoms, it is the number of electrons

  • Smaller than the atomic mass

  • Determines position of element on the periodic table

What is the nucleon/mass number?

• The total number of protons and neutrons in the nucleus of an atom

How to find number of neutrons or protons in an atom?

• Neutrons = Nucleon number - Proton number

• Protons = Nucleon number - Neutron number

What does group number (vertical column) determine in the periodic table?

• Number of valence electrons an element has

What does period number (horizontal row) determine in the periodic table?

• Number of electron shells an element has

How many electrons can each electron shell hold?

1. First electron shell: 2

2. Second electron shell: 8

3. Third electron shell: 8 

Determine the electronic configuration of elements with proton number 1 to 20

Proton number	Element (Symbol)	Shell Configuration
1	Hydrogen (H)	1
2	Helium (He)	2
3	Lithium (Li)	2, 1
4	Beryllium (Be)	2, 2
5	Boron (B)	2, 3
6	Carbon (C)	2, 4
7	Nitrogen (N)	2, 5
8	Oxygen (O)	2, 6
9	Fluorine (F)	2, 7
10	Neon (Ne)	2, 8
11	Sodium (Na)	2, 8, 1
12	Magnesium (Mg)	2, 8, 2
13	Aluminium (Al)	2, 8, 3
14	Silicon (Si)	2, 8, 4
15	Phosphorus (P)	2, 8, 5
16	Sulfur (S)	2, 8, 6
17	Chlorine (Cl)	2, 8, 7
18	Argon (Ar)	2, 8, 8
19	Potassium (K)	2, 8, 8, 1
20	Calcium (Ca)	2, 8, 8, 2

Describe the characteristics of noble gases

• Elements in group 8 are called the noble gases, and have a full outer shell of electrons

• All noble gases are unreactive, since their full electron shell makes them stable

• Atoms that are not noble gases want to reach a full configuration of electrons in the outer shell, so they bond with other atoms to get a full outer shell

Which are the diatomic elements in the periodic table?

• Have No Fear Of Ice Cold Beer

• Hydrogen, Nitrogen, Oxygen, Iodine, Chlorine, Bromine

What is the charge of elements in group 1-7?

• Group 1: 1+ (loses electron) - cation

• Group 2: 2+ (loses electrons) - cation

• Group 3: 3+ (loses electrons) - cation

• Group 4: 4+ or 4- (depends on element)

• Group 5: 3- (gains electrons) - anion

• Group 6: 2- (gains electrons) - anion

• Group 7: 1- (gains electron) - anion

Where are metals and non-metals located in the periodic table?

What group is the halogens? 

• Group 7