Chapter 1: Atoms and Elements

Question 1

Draw the simplified atomic model for Lithium

Answer 1

Lithium: 3 protons, 3 neutrons, 2 electrons in first shell, 1 in second.

Question 2

Draw the simplified atomic model for Aluminum

Answer 2

Aluminum: 13 protons, 14 neutrons, electrons distributed in shells 2, 8, 3.

Question 3

Draw the simplified atomic model for Argon

Answer 3

Argon: 18 protons, 22 neutrons, electrons in shells 2, 8, 8.

Question 4

What are ions?

Answer 4

Ions are atoms with an electric charge due to loss or gain of electrons.

Question 5

What is valence?

Answer 5

Valence is the charge of the ion or the number of electrons lost/gained.

Question 6

What are the ions and valences for B, Si, H, Ne, Cl, Mg?

Answer 6

• B³⁺
• Si⁴⁺ or Si⁴⁻ (depends on compound)
• H⁺ or H⁻
• Ne (neutral, noble gas)
• Cl⁻
• Mg²⁺

Question 7

What are the trends for atomic radius across a period?

Answer 7

Atomic radius decreases left to right.

Question 8

What are the trends for reactivity across a period?

Answer 8

Reactivity varies across a period.

Question 9

What are the trends for ionization energy across a period?

Answer 9

Ionization energy generally increases left to right.

Question 10

How does atomic radius change across a period?

Answer 10

The size of the atomic radius decreases as you move from left to right across a period.

Question 11

What is an isotope?

Answer 11

Atoms of the same element with different numbers of neutrons.

Question 12

What info do you have from isotopes ¹H¹, ¹H², ¹H³?

Answer 12

Hydrogen with 0, 1, and 2 neutrons respectively.

Question 13

What is Avogadro’s number?

Answer 13

6.02 × 10²³ particles per mole.

Question 14

What is a mole of zinc equal to?

Answer 14

6.02 × 10²³ atoms of zinc.

Question 15

Math problems (do the calculation):

Mass of 1.00 mol CO₂?

Mass of 2.0 mol C₆H₁₂O₆?

Mass of 0.03 mol NaCl?

Mass of 0.55 mol PCl₃?

Answer 15

1) Mass of 1.00 mol CO₂?

Molar mass CO₂ = C (12 g/mol) + 2 × O (16 g/mol) = 12 + 32 = 44 g/mol

Mass = 1.00 mol × 44 g/mol = 44 g

2) Mass of 2.0 mol C₆H₁₂O₆? (glucose)

Molar mass C₆H₁₂O₆ = 6×12 + 12×1 + 6×16 = 72 + 12 + 96 = 180 g/mol

Mass = 2.0 mol × 180 g/mol = 360 g

3) Mass of 0.03 mol NaCl?

Molar mass NaCl = Na (23 g/mol) + Cl (35.5 g/mol) = 58.5 g/mol

Mass = 0.03 mol × 58.5 g/mol = 1.755 g (round to 1.76 g)

4) Mass of 0.55 mol PCl₃?

Molar mass PCl₃ = P (31 g/mol) + 3 × Cl (35.5 g/mol) = 31 + 106.5 = 137.5 g/mol

Mass = 0.55 mol × 137.5 g/mol = 75.625 g (round to 75.63 g)