Matter

Question 1

What are the four main states of matter?

Answer 1

Solid, liquid, gas, and plasma.

Question 2

How are particles arranged in a solid?

Answer 2

Tightly packed, vibrating in fixed positions.

Question 3

How are particles arranged in a liquid?

Answer 3

Close together but able to slide past one another.

Question 4

How are particles arranged in a gas?

Answer 4

Far apart and moving freely and rapidly.

Question 5

What is melting?

Answer 5

Solid → liquid.

Question 6

What is vaporization?

Answer 6

Liquid → gas.

Question 7

What is condensation?

Answer 7

Gas → liquid.

Question 8

What is sublimation?

Answer 8

Solid → gas (skips liquid).

Question 9

What is deposition?

Answer 9

Gas → solid.

Question 10

What is dissolution?

Answer 10

Process where a solute dissolves in a solvent to form a solution.

Question 11

Do physical properties depend on size?

Answer 11

Intensive properties (density, boiling point) do NOT depend on size. Extensive properties (mass, volume) DO.

Question 12

How can physical properties identify substances?

Answer 12

By measuring density, melting point, boiling point, solubility, conductivity.

Question 13

What is viscosity?

Answer 13

Resistance to flow (unit: Pa·s). Liquids become less viscous when heated.

Question 14

What is surface tension?

Answer 14

Force at the surface of a liquid that minimizes surface area.

Question 15

What is specific heat?

Answer 15

Energy needed to raise 1 g of a substance by 1°C (J/g°C).

Question 16

How does temperature affect particle motion?

Answer 16

Higher temperature → faster particle movement.

Question 17

How does pressure affect gases?

Answer 17

Increasing pressure decreases volume (Boyle’s Law).

Question 18

Difference between elements, compounds, mixtures?

Answer 18

Element = one type of atom Compound = chemically bonded elements Mixture = physically combined substances

Question 19

What is a physical change?

Answer 19

Change in form without new substance (e.g., melting).

Question 20

What is a chemical change?

Answer 20

Formation of a new substance.

Question 21

Signs of chemical change?

Answer 21

Color change, gas formation, precipitate, heat/light, odor change.

Question 22

What are reactants?

Answer 22

Starting substances.

Question 23

What are products?

Answer 23

Substances formed.

Question 24

What is a chemical equation?

Answer 24

Symbolic representation of a reaction.

Question 25

Why must equations be balanced?

Answer 25

To obey the Law of Conservation of Mass.

Question 26

What is the Law of Conservation of Mass?

Answer 26

Mass is neither created nor destroyed.

Question 27

What is activation energy?

Answer 27

Minimum energy required to start a reaction.

Question 28

What is an endothermic reaction?

Answer 28

Absorbs energy.

Question 29

What is an exothermic reaction?

Answer 29

Releases energy.

Question 30

What is a catalyst?

Answer 30

Substance that speeds up a reaction without being used up.

Question 31

What is an inhibitor?

Answer 31

Substance that slows down a reaction.

Question 32

What affects reaction rate?

Answer 32

Temperature, concentration, surface area, pressure (for gases), catalysts.

Question 33

What are acids?

Answer 33

Substances that produce hydronium ions (H₃O⁺) in water.

Question 34

What are bases?

Answer 34

Substances that produce OH⁻ ions.

Question 35

What is neutralization?

Answer 35

Acid + base → salt + water.

Question 36

What is pH?

Answer 36

Measure of acidity (0–14 scale).

Question 37

What does low pH mean?

Answer 37

High acidity, more H₃O⁺ ions.

Question 38

What is an element symbol?

Answer 38

One- or two-letter abbreviation (e.g., H, Na).

Question 39

What is a chemical formula?

Answer 39

Shows elements and number of atoms (e.g., H₂O).

Question 40

How are elements arranged in the periodic table?

Answer 40

By increasing atomic number.

Question 41

What is atomic number?

Answer 41

Number of protons.

Question 42

What is mass number?

Answer 42

Protons + neutrons.

Question 43

What are isotopes?

Answer 43

Same element, different number of neutrons.

Question 44

What are periods?

Answer 44

Rows of the periodic table.

Question 45

What are groups?

Answer 45

Columns; same valence electrons.

Question 46

What are alkali metals?

Answer 46

Group 1, very reactive metals.

Question 47

What are noble gases?

Answer 47

Group 18, very unreactive.

Question 48

What are transition metals?

Answer 48

Middle block metals.

Question 49

What is electronic configuration?

Answer 49

Arrangement of electrons in energy levels.

Question 50

How does valence electron number affect reactivity?

Answer 50

Atoms react to achieve full outer shell.

Question 51

What is ionic bonding?

Answer 51

Transfer of electrons forming ions.

Question 52

What is covalent bonding?

Answer 52

Sharing of electrons.

Question 53

What is metallic bonding?

Answer 53

“Sea of electrons” shared among metal atoms.

Question 54

What is a polar molecule?

Answer 54

Unequal sharing of electrons.

Question 55

What is a nonpolar molecule?

Answer 55

Equal sharing of electrons.

Question 56

Why is the atom the basic unit of matter?

Answer 56

Smallest unit retaining chemical properties.

Question 57

What are atoms made of?

Answer 57

Protons, neutrons, electrons.

Question 58

Who proposed the first atomic theory?

Answer 58

John Dalton.

Question 59

What did Crookes discover?

Answer 59

Cathode rays.

Question 60

What did J.J. Thomson discover?

Answer 60

The electron.

Question 61

What did Rutherford discover?

Answer 61

The nucleus.

Question 62

What did Bohr propose?

Answer 62

Electrons orbit in energy levels.

Question 63

What is the modern atomic model?

Answer 63

Quantum mechanical model (electron cloud).

Question 64

What is the dual nature of electrons?

Answer 64

They behave as particles and waves.

Question 65

What are alpha particles?

Answer 65

Helium nuclei (2 protons + 2 neutrons).

Question 66

What is radioactive decay?

Answer 66

Spontaneous emission of radiation.

Question 67

What is half-life?

Answer 67

Time for half of a radioactive sample to decay.

Question 68

What are beta rays?

Answer 68

High-energy electrons emitted during decay.

Question 69

What is carbon dating?

Answer 69

Using Carbon-14 decay to determine age of fossils.

Question 70

What are quarks?

Answer 70

Fundamental particles that make up protons and neutrons.