States of Matter & Classification of Matter – Lecture Review

Question-and-Answer flashcards covering definitions, examples, classifications, properties, and separation techniques related to states of matter and the classification of matter.

What are the three classical states of matter?

Solid, liquid, and gas.

Define matter.

Anything that has mass and volume.

Give one example of a substance that is a solid, liquid, and gas at room temperature (25 °C).

Iron is a solid, water is a liquid, and oxygen is a gas.

What process changes a solid directly into a gas?

Sublimation.

What is the reverse of sublimation called?

Deposition (gas directly to solid).

Name two common substances that sublime at room conditions.

Iodine and naphthalene (mothballs).

Why is dry ice called “dry”?

Because solid CO₂ sublimes—it does not melt into a liquid under normal pressure.

State two everyday uses of dry ice.

Keeping ice-cream frozen and creating stage ‘fog’ in entertainment.

Formation of frost on a cold window is an example of which change of state?

Deposition of water vapor into ice crystals.

Which direction of temperature change (heating or cooling) causes condensation?

Cooling of a gas turns it into a liquid (condensation).

List the two broad categories of matter in the basic classification scheme.

Pure substances and impure substances (mixtures).

How do elements differ from compounds?

Elements contain only one kind of atom and cannot be chemically decomposed; compounds contain two or more kinds of atoms in a fixed ratio and can be decomposed chemically.

Give the chemical formula for table salt.

NaCl.

What are the two main types of mixtures?

Homogeneous mixtures and heterogeneous mixtures.

Provide two examples of homogeneous mixtures.

Salty water and air (nitrogen–oxygen mixture).

What heterogeneous mixture contains solid particles dispersed in a liquid?

A suspension (e.g., sand-water).

Oil and water form which specific type of heterogeneous mixture?

An emulsion.

State three characteristic properties of metals.

Good conductors of heat and electricity, lustrous, malleable/ductile (can be hammered or drawn into wire).

List three nonmetals that are gases at room temperature.

Hydrogen (H₂), nitrogen (N₂), and chlorine (Cl₂).

Which two elements are liquids at room temperature?

Mercury (Hg) – the only liquid metal, and bromine (Br₂) – the only liquid non-metal.

Define monoatomic element and give an example.

An element whose atoms exist singly (e.g., helium).

Name all seven diatomic elements remembered by ‘HONClBrIF’.

Hydrogen, oxygen, nitrogen, chlorine, bromine, iodine, fluorine.

What is a physical change?

A change that affects physical properties only, without altering chemical composition (e.g., melting ice).

Give two examples of chemical changes.

Rusting of iron and burning of wood.

Density formula.

Density (d) = mass (m) ÷ volume (V).

Does density depend on the amount of substance?

No, it is an intensive (characteristic) property.

Explain why ships float using density.

Average density of a ship (including air inside) is less than the density of water, so it floats.

State the melting and boiling points of water at 1 atm pressure.

Melting/freezing point 0 °C; boiling point 100 °C.

What happens to temperature during a pure substance’s phase change?

Temperature remains constant until the phase change is complete.

Do mixtures have definite melting points?

No; only pure substances have sharp melting/boiling points.

Define solubility.

Maximum mass of solute that dissolves in 100 g of solvent at a specific temperature.

Compare the solubility of table salt and sugar in 100 g of water.

Salt: about 36 g; sugar: about 190 g (at room temperature).

Which technique separates alcohol from water using boiling-point difference?

Fractional distillation.

How can a salt–chalk dust mixture be separated?

Add water (salt dissolves, chalk doesn’t), filter to remove chalk, then evaporate water to recover salt.

What property allows a magnet to separate powdered iron from sand?

Magnetism (iron is attracted, sand is not).

Name one separation method that uses density differences.

Using a separatory funnel to separate oil from water.

Which process decomposes water into hydrogen and oxygen?

Electrolysis (chemical decomposition).

What physical property difference allows paprika to be separated from salt using static electricity?

Paprika particles are attracted by static charge; salt crystals are not.

Define melting point.

The specific temperature at which a solid turns into a liquid under constant pressure.

State two common properties of matter that depend on the amount of sample.

Mass and volume.

List three characteristic properties (independent of amount).

Density, melting point, boiling point (also solubility).

Give the melting point of gold (Au) as cited in the notes.

Approximately 1063 °C.

When a liquid evaporates below its boiling point, what factor primarily drives the process?

Individual surface molecules gaining enough energy to escape into the gas phase (evaporation can occur at any temperature).

Why does density change with temperature?

Volume changes with temperature while mass stays constant, altering the mass/volume ratio.

Provide an example in which elements lose their original properties when forming a compound.

Sodium (a soft, reactive metal) and chlorine (a poisonous gas) combine to form table salt, a stable white solid.