chapter2

Question 1

What is an atom?

Answer 1

The atom is the fundamental unit of matter, composed of protons, neutrons, and electrons.

Question 2

What is the atomic number (Z)?

Answer 2

The atomic number (Z) is the number of protons in the nucleus.

Question 3

What is atomic mass (A)?

Answer 3

Atomic mass (A) is the total mass of protons and neutrons.

Question 4

What is Avogadro’s number (NA)?

Answer 4

Avogadro’s number (NA) is the number of atoms/molecules per mole: 6.022 x 10^23.

Question 5

What is an atomic mass unit (amu)?

Answer 5

An atomic mass unit (amu) is 1/12 of the mass of a carbon-12 atom.

Question 6

What is the approximate mass of an atom formula?

Answer 6

Mass of an atom (approx) = A * 1.66 x 10^-24 g.

Question 7

What is the Bohr model?

Answer 7

The Bohr model describes electrons revolving in discrete orbits; energy levels are quantized.

Question 8

What is the wave mechanical model?

Answer 8

The wave mechanical model describes electrons as probability clouds governed by quantum mechanics.

Question 9

What are quantum numbers?

Answer 9

Quantum numbers (QNs) describe the properties of electrons in atoms.

Question 10

What is the principal quantum number (n)?

Answer 10

The principal quantum number (n) indicates the energy level/shell (n = 1,2,3,…).

Question 11

What is the angular momentum quantum number (ℓ)?

Answer 11

The angular momentum quantum number (ℓ) indicates the subshell shape (ℓ = 0 to n-1).

Question 12

What are the possible values of ℓ?

Answer 12

The possible values of ℓ are: s (ℓ=0), p (ℓ=1), d (ℓ=2), f (ℓ=3).

Question 13

What is the magnetic quantum number (mℓ)?

Answer 13

The magnetic quantum number (mℓ) indicates the orbital orientation (-ℓ to +ℓ).

Question 14

What is the spin quantum number (ms)?

Answer 14

The spin quantum number (ms) indicates the electron spin (+½ or -½).

Question 15

What is the formula for maximum electrons in a subshell?

Answer 15

Max electrons = 2(2ℓ + 1).

Question 16

What is the Aufbau principle?

Answer 16

The Aufbau principle states to fill lowest energy levels first.

Question 17

What is Hund’s rule?

Answer 17

Hund’s rule states that electrons fill degenerate orbitals singly before pairing.

Question 18

What is the Pauli exclusion principle?

Answer 18

The Pauli exclusion principle states that no two electrons can have the same four quantum numbers.

Question 19

What is the electronic configuration of Sodium (Na, Z=11)?

Answer 19

1s² 2s² 2p⁶ 3s¹.

Question 20

What is the electronic configuration of Manganese (Mn, Z=25)?

Answer 20

1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d⁵.

Question 21

What are valence electrons?

Answer 21

Valence electrons are electrons in the outermost shell that participate in bonding.

Question 22

What is ionic bonding?

Answer 22

Ionic bonding is the transfer of electrons from metal to non-metal, forming cations and anions.

Question 23

What are the properties of ionic bonding?

Answer 23

Ionic bonding is strong, nondirectional, and has high melting points.

Question 24

What is an example of ionic bonding?

Answer 24

Examples include NaCl and MgO.

Question 25

What is covalent bonding?

Answer 25

Covalent bonding involves the sharing of electrons between atoms, usually non-metals.

Question 26

What are the types of covalent bonding?

Answer 26

Types include polar (unequal sharing) and non-polar (equal sharing).

Question 27

What is an example of polar covalent bonding?

Answer 27

An example is HCl.

Question 28

What is an example of non-polar covalent bonding?

Answer 28

Examples include Cl₂ and CH₄.

Question 29

What are multiple bonds in covalent bonding?

Answer 29

Multiple bonds include double bonds (e.g., O₂) and triple bonds (e.g., N₂).

Question 30

What are the properties of covalent bonding?

Answer 30

Covalent bonding is directional, forms hard solids or gases, and has high melting points.

Question 31

What are examples of covalent bonding?

Answer 31

Examples include SiC, CH₄, and H₂O.

Question 32

What is metallic bonding?

Answer 32

Metallic bonding is described by the electron sea model, where delocalized electrons surround ion cores.

Question 33

What are the properties of metallic bonding?

Answer 33

Metallic bonding is conductive, ductile, malleable, and has high melting points.

Question 34

What are examples of metallic bonding?

Answer 34

Examples include Fe, Cu, and Al.

Question 35

What are secondary bonds?

Answer 35

Secondary bonds, also known as Van der Waals bonds, are weaker than primary bonds.

Question 36

What are dipole-dipole interactions?

Answer 36

Dipole-dipole interactions are a type of secondary bonding.

Question 37

What is hydrogen bonding?

Answer 37

Hydrogen bonding is the strongest among secondary bonds, found in H₂O, NH₃, and HF.

Question 38

What are fluctuating dipoles?

Answer 38

Fluctuating dipoles are temporary induced dipoles, such as in liquid H₂.

Question 39

What are the properties of secondary bonds?

Answer 39

Secondary bonds are weaker than primary bonds and influence melting/boiling points and solubility.

Question 40

What are the general material properties by bond type?

Answer 40

Ionic: brittle, hard, high melting point, soluble, conductive in solution; Covalent: high strength, directional, non-conductive; Metallic: conductive, malleable, ductile; Secondary: weak bonding, soft, volatile.

Question 41

What is the key takeaway about atomic structure and bonding?

Answer 41

Understanding atomic structure and bonding helps explain material properties such as strength, conductivity, melting point, and chemical reactivity.