chemia

Question 1

What is matter?

Answer 1

Anything that has mass and occupies space.

Question 2

Name and describe basic states of matter.

Answer 2

Solid: definite shape/volume; Liquid: definite volume, no definite shape; Gas: no definite shape/volume; Plasma: ionized gas.

Question 3

Describe ionic crystals.

Answer 3

Lattice of positive and negative ions, hard, brittle, high melting point, conducts electricity in molten state.

Question 4

Describe atomic crystals.

Answer 4

Covalently bonded atoms, very hard, extremely high melting points (e.g., diamond).

Question 5

Describe molecular crystals.

Answer 5

Molecules held by weak forces, soft, low melting point (e.g., ice).

Question 6

Describe foliaceous crystals.

Answer 6

Layered structures, easy to split into sheets (e.g., mica).

Question 7

Describe metallic crystals.

Answer 7

Positive ions in a sea of delocalized electrons, good conductors (e.g., copper).

Question 8

Define element.

Answer 8

A pure substance made of only one type of atom.

Question 9

Define compound.

Answer 9

Substance made of two or more different elements chemically bonded.

Question 10

Define molecule.

Answer 10

Two or more atoms bonded together.

Question 11

Define homogeneous mixture.

Answer 11

Mixture with uniform composition (e.g., saltwater).

Question 12

Define heterogeneous mixture.

Answer 12

Mixture with variable composition (e.g., sand and iron filings).

Question 13

Define colloid.

Answer 13

Mixture where particles don’t settle (e.g., milk).

Question 14

Define isolated system.

Answer 14

No exchange of matter or energy.

Question 15

Define closed system.

Answer 15

Exchanges energy but not matter.

Question 16

Define open system.

Answer 16

Exchanges both energy and matter.

Question 17

Name methods of separating mixtures.

Answer 17

Filtration, distillation, evaporation, centrifugation, chromatography.

Question 18

How to separate a mixture of NaCl, sulfur, and water?

Answer 18

Filtration to remove sulfur, evaporation to recover NaCl.

Question 19

Define solution.

Answer 19

Homogeneous mixture of solute dissolved in solvent.

Question 20

Define solvent.

Answer 20

The substance that dissolves the solute.

Question 21

Define solute.

Answer 21

The substance being dissolved.

Question 22

Define solubility.

Answer 22

Maximum amount of solute that can dissolve in solvent at given temperature.

Question 23

What is a solubility curve?

Answer 23

Graph showing solubility vs temperature.

Question 24

Name types of solutions.

Answer 24

Gaseous (air), Liquid (saltwater), Solid (alloy).

Question 25

Ways to express composition of solution.

Answer 25

Mass fraction (w), Volume fraction (ф), Concentration (c), Density (ρ).

Question 26

Describe nucleus and electron shell.

Answer 26

Nucleus contains protons and neutrons; electrons orbit in shells.

Question 27

Define orbital.

Answer 27

Region where electron is likely found around nucleus.

Question 28

List the four quantum numbers.

Answer 28

Principal (n), Azimuthal (l), Magnetic (m), Spin (s).

Question 29

State the Aufbau principle.

Answer 29

Electrons fill lowest energy orbitals first.

Question 30

State the Pauli Exclusion Principle.

Answer 30

No two electrons have the same four quantum numbers.

Question 31

State Hund’s Rule.

Answer 31

Electrons occupy orbitals singly first.

Question 32

Full electron configuration of Cl.

Answer 32

1s² 2s² 2p⁶ 3s² 3p⁵

Question 33

Full electron configuration of Cr.

Answer 33

1s² 2s² 2p⁶ 3s² 3p⁶ 3d⁵ 4s¹

Question 34

Full electron configuration of Si.

Answer 34

1s² 2s² 2p⁶ 3s² 3p²

Question 35

Full electron configuration of Mg.

Answer 35

1s² 2s² 2p⁶ 3s²

Question 36

Condensed configuration of S.

Answer 36

[Ne] 3s² 3p⁴

Question 37

Condensed configuration of Na.

Answer 37

[Ne] 3s¹

Question 38

Condensed configuration of I.

Answer 38

[Kr] 4d¹⁰ 5s² 5p⁵

Question 39

Condensed configuration of Cu.

Answer 39

[Ar] 3d¹⁰ 4s¹

Question 40

Classify Na, Mg, Cl, S, Si, Cr, Cu, I as s, p, d, or f block.

Answer 40

s-block: Na, Mg; p-block: Cl, S, Si, I; d-block: Cr, Cu.

Question 41

Compare properties of alkali metals.

Answer 41

Large radius, low ionization energy, low electronegativity, metallic.

Question 42

Compare properties of 3d elements.

Answer 42

Smaller radius, higher ionization energy, moderate electronegativity, metallic.

Question 43

Electron configuration of carbon in excited state.

Answer 43

1s² 2s¹ 2p³

Question 44

Electron configuration of S²⁻ ion.

Answer 44

1s² 2s² 2p⁶ 3s² 3p⁶

Question 45

Electron configuration of Na⁺ ion.

Answer 45

1s² 2s² 2p⁶

Question 46

Electron configuration of Cr²⁺ ion.

Answer 46

[Ar] 3d⁴

Question 47

Define binding capacity.

Answer 47

Number of bonds an atom can form.

Question 48

Define dissociation energy.

Answer 48

Energy needed to break a bond.

Question 49

Define electronegativity.

Answer 49

Tendency to attract electrons.

Question 50

Explain chemical bond formation.

Answer 50

Atoms bond to achieve stability (full outer shell).

Question 51

Example of covalent bond.

Answer 51

Water (H₂O).

Question 52

Example of ionic bond.

Answer 52

Sodium chloride (NaCl).

Question 53

Example of coordination bond.

Answer 53

Ammonium ion (NH₄⁺).

Question 54

Example of metallic bond.

Answer 54

Iron (Fe).

Question 55

What is a sigma bond?

Answer 55

Head-on overlap of orbitals (single bond).

Question 56

What is a pi bond?

Answer 56

Side-by-side overlap of p orbitals.

Question 57

Binding capacity and state in HBr.

Answer 57

H (1), Br (1); ground state.

Question 58

Binding capacity and state in CO₂.

Answer 58

C (4), O (2); C in excited state.

Question 59

Binding capacity and state in BeCl₂.

Answer 59

Be (2), Cl (1); Be in excited state.

Question 60

Binding capacity and state in HCN.

Answer 60

H (1), C (4), N (3); C in excited state.

Question 61

Type of bond in O₂.

Answer 61

Covalent (double bond).

Question 62

Type of bond in H₂O.

Answer 62

Covalent (polar).

Question 63

Type of bond in CO.

Answer 63

Covalent with partial dative bond.

Question 64

Type of bond in NaCl.

Answer 64

Ionic.

Question 65

Shape and hybridization of CH₄.

Answer 65

Tetrahedral, sp³.

Question 66

Shape and hybridization of BF₃.

Answer 66

Trigonal planar, sp².

Question 67

Shape and hybridization of BeCl₂.

Answer 67

Linear, sp.

Question 68

Shape and hybridization of H₂O.

Answer 68

Bent, sp³.