Question

practice table - valence electrons & atoms vs. ions
fill in the chart below
name | symbol | # of valence electrons | p | e | atomic # | charge | gained or lost e neutral | atom, cation, anion
boron atom | | | | | | | |

		20			+2
			18		-3
			36		0
		3			+1
		17			-1

Answer:

To solve the table, we use the following concepts:

• Atomic number (\(Z\)) = number of protons (\(p^+\)) = number of electrons (\(e^-\)) in a neutral atom.
• Charge = \(p^+ - e^-\) (for ions, \(e^- = p^+ - \text{charge}\) if charge is positive, \(e^- = p^+ + |\text{charge}|\) if charge is negative).
• Valence electrons: For main - group elements, group number (1 - 2, 13 - 18) gives valence electrons (e.g., Group 1: 1, Group 2: 2, Group 13: 3, Group 14: 4, Group 15: 5, Group 16: 6, Group 17: 7, Group 18: 8).

1. Boron atom

• Symbol: \(B\) (atomic number 5, Group 13).
• # of Valence electrons: Group 13 → 3.
• \(p^+\): Atomic number = 5 → \(p^+ = 5\).
• \(e^-\): Neutral atom → \(e^- = p^+ = 5\).
• Atomic #: \(p^+ = 5\) → 5.
• Charge: Neutral → 0.
• Gained or Lost \(e^-\): Neutral → neither.
• Atom, cation, anion: Atom.

2. Ion with \(p^+ = 20\), Charge = \(+2\)

• \(p^+\) = 20 → Atomic number 20 (Calcium, \(Ca\)).
• \(e^-\): \(e^- = p^+ - \text{charge} = 20 - 2 = 18\).
• Atomic #: \(p^+ = 20\) → 20.
• # of Valence electrons: Calcium is Group 2 → 2 (lost 2 electrons to form \(Ca^{2+}\)).
• Name: Calcium ion (\(Ca^{2+}\)).
• Symbol: \(Ca^{2+}\).
• Gained or Lost \(e^-\): Lost 2.
• Atom, cation, anion: Cation.

3. Ion with \(e^- = 18\), Charge = \(-3\)

• \(e^-\) = 18, Charge = \(-3\) → \(p^+ = e^- - |\text{charge}| = 18 - 3 = 15\) (Phosphorus, \(P\)).
• Atomic #: \(p^+ = 15\) → 15.
• # of Valence electrons: Phosphorus is Group 15 → 5 (gained 3 electrons to form \(P^{3-}\)).
• Name: Phosphide ion (\(P^{3-}\)).
• Symbol: \(P^{3-}\).
• \(p^+\): 15.
• Gained or Lost \(e^-\): Gained 3.
• Atom, cation, anion: Anion.

4. Neutral atom with \(e^- = 36\)

• Neutral atom → \(p^+ = e^- = 36\) (Krypton, \(Kr\), Group 18).
• Atomic #: 36.
• # of Valence electrons: Group 18 → 8.
• Name: Krypton atom.
• Symbol: \(Kr\).
• \(p^+\): 36.
• Charge: 0.
• Gained or Lost \(e^-\): Neither.
• Atom, cation, anion: Atom.

5. Ion with \(p^+ = 3\), Charge = \(+1\)

• \(p^+ = 3\) → Atomic number 3 (Lithium, \(Li\)).
• \(e^-\): \(e^- = p^+ - \text{charge} = 3 - 1 = 2\).
• Atomic #: 3.
• # of Valence electrons: Lithium is Group 1 → 1 (lost 1 electron to form \(Li^+\)).
• Name: Lithium ion (\(Li^+\)).
• Symbol: \(Li^+\).
• Gained or Lost \(e^-\): Lost 1.
• Atom, cation, anion: Cation.

6. Ion with \(p^+ = 17\), Charge = \(-1\)

• \(p^+ = 17\) → Atomic number 17 (Chlorine, \(Cl\)).
• \(e^-\): \(e^- = p^+ + |\text{charge}| = 17 + 1 = 18\).
• Atomic #: 17.
• # of Valence electrons: Chlorine is Group 17 → 7 (gained 1 electron to form \(Cl^-\)).
• Name: Chloride ion (\(Cl^-\)).
• Symbol: \(Cl^-\).
• Gained or Lost \(e^-\): Gained 1.
• Atom, cation, anion: Anion.

Filled Table (Key Columns):

Name	Symbol	# of Valence electrons	\(p^+\)	\(e^-\)	Atomic #	Charge	Gained/Lost \(e^-\)	Atom/Cation/Anion
Calcium ion	\(Ca^{2+}\)	2 (lost 2)	20	18	20	\(+2\)	Lost 2	Cation
Phosphide ion	\(P^{3-}\)	5 (gained 3)	15	18	15	\(-3\)	Gained 3	Anion
Krypton atom	\(Kr\)	8	36	36	36	0	Neither	Atom
Lithium ion	\(Li^+\)	1 (lost 1)	3	2	3	\(+1\)	Lost 1	Cation
Chloride ion	\(Cl^-\)	7 (gained 1)	17	18	17	\(-1\)	Gained 1	Anion

(Note: The last column "Atom, cation, anion" is filled as per the species type, and "Gained a Lost e Neutral" is interpreted as "Gained or Lost \(e^-\), Neutral" and filled accordingly.)