3. how many valence electrons do the following elements have?
___ fr ___ o ___ ne ___ c ___ mg ___ cl ___ al
14. identify the following atom, $1s^22s^22p^63s^1$ v.e.? ___
15. identify the following atom, $1s^22s^22p^6$ v.e.? ___
16. identify the following atom, $1s^22s^22p^63s^23p^64s^2$ v.e.? ___
17. identify the following atom, $1s^22s^22p^63s^23p^64s^23d^6$ v.e.? ___
18. fill in the table:
| element | electron configuration | noble gas electron configuration |
|---------|------------------------|----------------------------------|
| chlorine | | |
| cesium | | |
| tin | | |
19. fill in the table:
| element | period # | group # | valence electron s | oxidation number | gain or lose e? | cation or anion? |
|---------|----------|---------|--------------------|------------------|-----------------|------------------|
| sulfur | | | | | | |
| bromine | | | | | | |
| boron | | | | | | |
| strontium | | | | | | |
| potassium | | | | | | |
| neon | | | | | | |
20. fill in the table:
| element | period # | group # | group name | e-dot diagram | ox. # | # of valance e⁻ |
|---------|----------|---------|------------|---------------|-------|-----------------|
| $2s^2$ | | | | | | |
| $3s^23p^3$ | | | | | | |
| $3s^23p^6$ | | | | | | |
| $4s^1$ | | | | | | |

Question

3. how many valence electrons do the following elements have?
___ fr ___ o ___ ne ___ c ___ mg ___ cl ___ al
14. identify the following atom, $1s^22s^22p^63s^1$  v.e.? ___
15. identify the following atom, $1s^22s^22p^6$  v.e.? ___
16. identify the following atom, $1s^22s^22p^63s^23p^64s^2$  v.e.? ___
17. identify the following atom, $1s^22s^22p^63s^23p^64s^23d^6$  v.e.? ___
18. fill in the table:
| element | electron configuration | noble gas electron configuration |
|---------|------------------------|----------------------------------|
| chlorine |                        |                                  |
| cesium   |                        |                                  |
| tin      |                        |                                  |
19. fill in the table:
| element | period # | group # | valence electron s | oxidation number | gain or lose e? | cation or anion? |
|---------|----------|---------|--------------------|------------------|-----------------|------------------|
| sulfur  |          |         |                    |                  |                 |                  |
| bromine |          |         |                    |                  |                 |                  |
| boron   |          |         |                    |                  |                 |                  |
| strontium |        |         |                    |                  |                 |                  |
| potassium |        |         |                    |                  |                 |                  |
| neon    |          |         |                    |                  |                 |                  |
20. fill in the table:
| element | period # | group # | group name | e-dot diagram | ox. # | # of valance e⁻ |
|---------|----------|---------|------------|---------------|-------|-----------------|
| $2s^2$  |          |         |            |               |       |                 |
| $3s^23p^3$ |        |         |            |               |       |                 |
| $3s^23p^6$ |        |         |            |               |       |                 |
| $4s^1$  |          |         |            |               |       |                 |

Accepted Answer

### Problem 3: Valence Electrons of Elements
Let's solve for each element:

#### Francium (Fr)
Fr is in Group 1 (Alkali Metals). Group 1 elements have 1 valence electron.

#### Oxygen (O)
O is in Group 16 (Chalcogens). Valence electrons = Group number - 10 (for main groups 13–18) → $ 16 - 10 = 6 $.

#### Neon (Ne)
Ne is a noble gas (Group 18). Noble gases have 8 valence electrons (except He, which has 2).

#### Carbon (C)
C is in Group 14. Valence electrons = $ 14 - 10 = 4 $.

#### Magnesium (Mg)
Mg is in Group 2 (Alkaline Earth Metals). Group 2 elements have 2 valence electrons.

#### Chlorine (Cl)
Cl is in Group 17 (Halogens). Valence electrons = $ 17 - 10 = 7 $.

#### Aluminum (Al)
Al is in Group 13. Valence electrons = $ 13 - 10 = 3 $.

### Problem 14: Identify Atom from Electron Configuration ($ 1s^2 2s^2 2p^6 3s^1 $)
1. Sum the exponents: $ 2 + 2 + 6 + 1 = 11 $.
2. Atomic number 11 is Sodium (Na).
3. Valence electrons: The outermost shell is $ 3s^1 $, so 1 valence electron.

### Problem 15: Identify Atom from Electron Configuration ($ 1s^2 2s^2 2p^6 $)
1. Sum the exponents: $ 2 + 2 + 6 = 10 $.
2. Atomic number 10 is Neon (Ne).
3. Valence electrons: Neon is a noble gas, so 8 valence electrons.

### Problem 16: Identify Atom from Electron Configuration ($ 1s^2 2s^2 2p^6 3s^2 3p^6 4s^2 $)
1. Sum the exponents: $ 2 + 2 + 6 + 2 + 6 + 2 = 20 $.
2. Atomic number 20 is Calcium (Ca).
3. Valence electrons: Outermost shell $ 4s^2 $, so 2 valence electrons.

### Problem 17: Identify Atom from Electron Configuration ($ 1s^2 2s^2 2p^6 3s^2 3p^6 3d^8 4s^2 $)
1. Sum the exponents: $ 2 + 2 + 6 + 2 + 6 + 8 + 2 = 28 $.
2. Atomic number 28 is Nickel (Ni).
3. Valence electrons: For transition metals, valence electrons include $ 4s $ and $ 3d $, but typically $ 4s^2 $ (so 2, though some sources consider $ 3d^8 4s^2 $ as 10, but common for Ni: 2 or 10; here, $ 4s^2 $ gives 2).

### Problem 18: Electron Configurations & Noble Gas Configurations

#### Chlorine (Cl, Atomic #17)
- Electron Configuration: $ 1s^2 2s^2 2p^6 3s^2 3p^5 $
- Noble Gas Configuration: Use Ne ($ 1s^2 2s^2 2p^6 $) → $ [\text{Ne}] 3s^2 3p^5 $

#### Cesium (Cs, Atomic #55)
- Electron Configuration: $ 1s^2 2s^2 2p^6 3s^2 3p^6 4s^2 3d^{10} 4p^6 5s^2 4d^{10} 5p^6 6s^1 $
- Noble Gas Configuration: Use Xe ($ [\text{Kr}] 4d^{10} 5s^2 5p^6 $) → $ [\text{Xe}] 6s^1 $

#### Tin (Sn, Atomic #50)
- Electron Configuration: $ 1s^2 2s^2 2p^6 3s^2 3p^6 4s^2 3d^{10} 4p^6 5s^2 4d^{10} 5p^2 $
- Noble Gas Configuration: Use Kr ($ [\text{Ar}] 3d^{10} 4s^2 4p^6 $) → $ [\text{Kr}] 5s^2 4d^{10} 5p^2 $

### Problem 19: Element Properties Table

| Element   | Period # | Group # | Valence e⁻ | Oxidation Number | Gain or Lose e⁻? | Cation or Anion? |
|-----------|----------|---------|------------|------------------|------------------|------------------|
| Sulfur (S)| 3        | 16      | 6          | -2 (common)      | Gain 2           | Anion (S²⁻)      |
| Bromine (Br)| 4      | 17      | 7          | -1 (common)      | Gain 1           | Anion (Br⁻)      |
| Boron (B) | 2        | 13      | 3          | +3 (common)      | Lose 3           | Cation (B³⁺)     |
| Strontium (Sr)| 5    | 2       | 2          | +2 (common)      | Lose 2           | Cation (Sr²⁺)    |
| Potassium (K)| 4     | 1       | 1          | +1 (common)      | Lose 1           | Cation (K⁺)      |
| Neon (Ne) | 2        | 18      | 8          | 0 (noble gas)    | Neither          | None             |

### Problem 20: Element Properties from Electron Configuration

| Element (Electron Config) | Period # | Group # | Group Name       | E-dot Diagram (Valence e⁻) | Ox. # | # of Valence e⁻ |
|---------------------------|----------|---------|------------------|----------------------------|-------|-----------------|
| $ 2s^2 $ (Beryllium, Be) | 2        | 2       | Alkaline Earth   | $ \cdot \text{Be} \cdot $ (2 dots) | +2    | 2               |
| $ 3s^2 3p^3 $ (Phosphorus, P) | 3      | 15      | Pnictogen        | $ \cdot \text{P} \cdot $ (5 dots) | -3, +3, +5 | 5               |
| $ 3s^2 3p^6 $ (Argon, Ar) | 3        | 18      | Noble Gas        | $ [\text{Ar}] $ (8 dots) | 0     | 8               |
| $ 4s^1 $ (Potassium, K) | 4        | 1       | Alkali Metal     | $ \cdot \text{K} $ (1 dot) | +1    | 1               |

### Answers (Key Highlights):

#### Problem 3:
- Fr: 1
- O: 6
- Ne: 8
- C: 4
- Mg: 2
- Cl: 7
- Al: 3

#### Problem 14:
- Atom: Na (Sodium)
- Valence e⁻: 1

#### Problem 15:
- Atom: Ne (Neon)
- Valence e⁻: 8

#### Problem 16:
- Atom: Ca (Calcium)
- Valence e⁻: 2

#### Problem 17:
- Atom: Ni (Nickel)
- Valence e⁻: 2 (or 10, context-dependent)

#### Problem 18:
| Element   | Electron Configuration              | Noble Gas Configuration       |
|-----------|-------------------------------------|-------------------------------|
| Chlorine  | $ 1s^2 2s^2 2p^6 3s^2 3p^5 $      | $ [\text{Ne}] 3s^2 3p^5 $    |
| Cesium    | $ [\text{Xe}] 6s^1 $ (simplified) | $ [\text{Xe}] 6s^1 $         |
| Tin       | $ [\text{Kr}] 5s^2 4d^{10} 5p^2 $ | $ [\text{Kr}] 5s^2 4d^{10} 5p^2 $ |

#### Problem 19: (See table above)

#### Problem 20: (See table above)

Sovi.AI - AI Math Tutor

QUESTION IMAGE

Question

Explanation:

Problem 3: Valence Electrons of Elements

Francium (Fr)

Oxygen (O)

Neon (Ne)

Carbon (C)

Magnesium (Mg)

Chlorine (Cl)

Aluminum (Al)

Problem 14: Identify Atom from Electron Configuration (\( 1s^2 2s^2 2p^6 3s^1 \))

Problem 15: Identify Atom from Electron Configuration (\( 1s^2 2s^2 2p^6 \))

Problem 16: Identify Atom from Electron Configuration (\( 1s^2 2s^2 2p^6 3s^2 3p^6 4s^2 \))

Problem 17: Identify Atom from Electron Configuration (\( 1s^2 2s^2 2p^6 3s^2 3p^6 3d^8 4s^2 \))

Problem 18: Electron Configurations & Noble Gas Configurations

Chlorine (Cl, Atomic #17)

Cesium (Cs, Atomic #55)

Tin (Sn, Atomic #50)

Problem 19: Element Properties Table

Problem 20: Element Properties from Electron Configuration

Answer:

Problem 3:

Problem 14:

Problem 15:

Problem 16:

Problem 17:

Problem 18:

Problem 19: (See table above)

Problem 20: (See table above)

Element	Period #	Group #	Valence e⁻	Oxidation Number	Gain or Lose e⁻?	Cation or Anion?
Bromine (Br)	4	17	7	-1 (common)	Gain 1	Anion (Br⁻)
Boron (B)	2	13	3	+3 (common)	Lose 3	Cation (B³⁺)
Strontium (Sr)	5	2	2	+2 (common)	Lose 2	Cation (Sr²⁺)
Potassium (K)	4	1	1	+1 (common)	Lose 1	Cation (K⁺)
Neon (Ne)	2	18	8	0 (noble gas)	Neither	None

Element	Electron Configuration	Noble Gas Configuration
Cesium	\( [\text{Xe}] 6s^1 \) (simplified)	\( [\text{Xe}] 6s^1 \)
Tin	\( [\text{Kr}] 5s^2 4d^{10} 5p^2 \)	\( [\text{Kr}] 5s^2 4d^{10} 5p^2 \)