Year 8 Chemistry Exam Study Guide

Flashcards for Year 8 Chemistry Exam Review

What is the Kinetic Molecular Theory (KMT)?

Explains the behavior of particles in matter, stating all matter is made of tiny particles in constant motion, with the speed of particles increasing as temperature increases.

Describe the particle motion, arrangement, compressibility, and examples of solids, liquids, and gases.

Solid: Vibrate in place, tightly packed, fixed shape, no compressibility (Example: Ice cube). Liquid: Slide past each other, close together, not fixed, slightly compressible (Example: Water). Gas: Move quickly in all directions, far apart, highly compressible (Example: Air).

How does temperature affect particle movement?

Higher temperature leads to faster particle motion, while lower temperature results in slower particle motion.

Describe the energy changes during phase transitions (melting, freezing, boiling, condensation, sublimation, deposition).

Melting (Solid to Liquid): Gains energy. Freezing (Liquid to Solid): Loses energy. Boiling (Liquid to Gas): Gains a lot of energy. Condensation (Gas to Liquid): Loses energy. Sublimation (Solid to Gas): Gains energy. Deposition (Gas to Solid): Loses energy.

What causes gas pressure, and how do temperature and volume affect it?

Gas pressure is caused by particles colliding with the walls of a container. Increasing temperature raises pressure, while decreasing volume increases pressure.

What is the formula for density, and what are its units?

Density = Mass / Volume. Units for solids are g/cm³, and for liquids, g/mL.

How do temperature and pressure relate to volume and density?

Temperature increase leads to volume expansion and density decrease. Pressure increase results in volume compression and density increase.

Describe the charge, location, and effects of protons, neutrons, and electrons.

Proton: +1 charge, located in the nucleus, affects atomic number (identity). Neutron: 0 charge, located in the nucleus, affects mass number. Electron: -1 charge, located in shells around the nucleus, affects charge and chemical behavior.

How are atomic number and mass number defined?

Atomic Number = Number of Protons. Mass Number = Protons + Neutrons.

What do Bohr diagrams show and what are the rules for electron arrangement?

Show electrons in shells around the nucleus, with a maximum of 2 electrons in the 1st shell, 8 in the 2nd, and 18 in the 3rd.

What are groups and periods in the periodic table?

Groups are vertical columns with elements having similar properties due to the same valence electrons. Periods are horizontal rows indicating the number of electron shells.

Describe the particle arrangement in solids, liquids and gasses.

Solid: Structured, tight. Liquid: Loose. Gas: Spread out.

Explain the changes during the melting phase transition:

Solid becomes Liquid, Heat energy is absorbed, Particles gain energy, vibrate faster, and break free from their fixed positions

Explain the changes during the boiling phase transition:

Liquid becomes Gas, Particles gain enough energy to escape into gas form from all parts of the liquid

Explain the changes during the condensation phase transition:

Gas becomes Liquid, Energy is lost, Particles slow down and come closer

Explain the changes during the freezing phase transition:

Liquid becomes Solid, Energy is removed, Particles slow down and form a fixed pattern

How does a high temperature affect particle motion & density in gases?

High temp = more kinetic energy → particles move faster → volume increases → density decreases

How does increased pressure affect particle motion & density in gases?

Increased pressure = volume decreases → particles are closer → density increases