Question

1. new terms
2. the rings in the bohr model are called ______ or energy levels.
3. the number of shells an element has can be found using the row number in the ______. the number of electron shell is the same as the period number for representative elements.
4. all electrons not in the highest energy level are called ______ electrons.
5. all electrons in the highest energy level or outermost electron shell are called ______ electrons.
6. to find the number of core electrons:

a. total electrons - valence electrons = ______
b. total electrons - core electron = ______

1. complete the periodic table below by filling in the number of valence electrons in each column.

1a	2a	d - block	3a	4a	5a	6a	7a	8a

1. practice finding the number of core electrons, valence electrons and number of energy level. use your periodic table to identify the # of core electrons, valence electrons

	lithium, ₃li	sodium, ₁₁na	oxygen, ₈o	neon, ₁₀ne
# valence electron
total # electron

Explanation:

Step1: Recall Bohr - model terms

In the Bohr Model, the "rings" are called electron shells or energy levels.

Step2: Determine shell - finding method

The number of shells an element has can be found using the row number in the periodic table.

Step3: Define electron types

Electrons not in the highest energy level are called core electrons. Electrons in the highest energy level or outermost electron shell are called valence electrons.

Step4: Calculate core electrons

To find the number of core electrons, we use the formula: Total electrons - valence electrons = core electrons. Also, Total electrons - core electrons = valence electrons.

Step5: Fill periodic - table valence - electron numbers

For group 1A, the number of valence electrons is 1; for group 2A, it is 2; for group 3A, it is 3; for group 4A, it is 4; for group 5A, it is 5; for group 6A, it is 6; for group 7A, it is 7; for group 8A, it is 8. For the d - block elements, the number of valence electrons can vary but is generally 2 (with some exceptions due to involvement of d - electrons in bonding).

Step6: Find electron numbers for given elements

• Lithium ($Li$): Atomic number = 3. Total electrons = 3. It is in group 1A, so valence electrons = 1. Core electrons = 3 - 1=2.
• Sodium ($Na$): Atomic number = 11. Total electrons = 11. It is in group 1A, so valence electrons = 1. Core electrons = 11 - 1 = 10.
• Oxygen ($O$): Atomic number = 8. Total electrons = 8. It is in group 6A, so valence electrons = 6. Core electrons = 8 - 6 = 2.
• Neon ($Ne$): Atomic number = 10. Total electrons = 10. It is in group 8A, so valence electrons = 8. Core electrons = 10 - 8 = 2.

Answer:

1. Electron Shells
2. Periodic Table
3. Core
4. Valence
5. a. Core electrons; b. Valence electrons
6. 1A: 1; 2A: 2; d - block: 2 (general); 3A: 3; 4A: 4; 5A: 5; 6A: 6; 7A: 7; 8A: 8

7)

Element	# core electrons	# valence electrons	Total # electrons
Sodium ($Na$)	10	1	11
Oxygen ($O$)	2	6	8
Neon ($Ne$)	2	8	10