yhs gr. 8 chemistry test

What is a physical property?

A characteristic that can be observed or measured without changing its chemical identity (the type of matter that it is).

Difference between qualitative and quantitative properties?

Qualitative: no measurements, descriptive words, uses the 5 senses. Quantitative: can be measured, is assigned a value.

What are the three states of matter?

Solid, liquid, gas.

4 main points of the KMT? kinetic molecular theory

1. All matter is made up of very small particles

2. There is empty space between particles.

3. Particles are constantly moving. In liquids and gases, they are colliding with each other and the walls of their container. In solids, they are only able to vibrate.

4. Energy makes particles move.

4 main points of the PMM? particle model of matter

1. All matter is made of very small particles (atoms)

2. There are spaces between the particles and the amount of space depends on the state of matter.

3. These particles are always moving.

4. The particles are attracted to each other. The strength of the attraction depends on the types of particle.

What is kinetic energy?

The energy of motion.

Main difference between the KMT and the PMM?

They are similar but the KMT also includes how matter behaves when the kinetic energy of the particles changes.

How does kinetic energy affect particles?

more KE = faster movement + less attraction = particles move farther apart

Difference between heat, temperature, and thermal energy

Heat: Energy transferred between objects

Temperature: Average kinetic energy of particles

Thermal energy: Total energy of all particles in a substance

What is mass?

Mass is the amount of matter in an object.

Units for mass?

grams (g) or kilograms (kg)

What is volume?

Volume is the amount of space an object takes up.

Units for volume?

milliliters (mL), liters (L), or cubic centimeters (cm³)

Density equation

Density = Mass ÷ Volume

Mass equation

Mass = Density x Volume

Volume equation

Volume = Mass ÷ Density

What is matter?

Matter is anything that has mass and volume.

What is a heterogeneous (mechanical) mixture?

A mixture that contains particles of different substances that remain clumped together.

What is a homogeneous (solution) mixture?

A mixture contains particles of the different substances that are completely mixed together.

Changes of state?

Melting: Solid → Liquid

Freezing: Liquid → Solid

Evaporation: Liquid → Gas

Condensation: Gas → Liquid

Sublimation: Solid → Gas

Deposition: Gas → Solid

Physical vs chemical changes

Physical: No new substance formed (e.g., melting ice)

Chemical: New substance formed (e.g., rotting)

What was John Dalton's contribution to the Atomic Theory?

Dalton proposed that all matter is composed of tiny, indivisible particles called atoms. He said that atoms of the same element have the same mass and properties, and atoms of different elements vary.

What was J.J. Thomson's contribution to the Atomic Theory?

Thomson discovered electrons. He made a "raisin bun" model of the atom which was a positively charged ball with negatively charged particles called electrons embedded in the ball.

What was Ernest Rutherford's contribution to the Atomic Theory?

Rutherford discovered the nucleus and proposed that they were the tiny, dense, positively charged centre of the atom. He also said that there must be at least 2 kinds of particles inside the nucleus of an atom (protons - positive electric charge, and neutrons - no electric charge)

What was Neils Bohr's contribution to the Atomic Theory?

Bohr proposed that electrons surround the nucleus in "orbits" and he also said that electrons surround the nucleus in specific electron shells. He finally stated that each electron has a specific amount of energy.

What are the three subatomic particles called?

Protons, neutrons, electrons.

Proton details

Charge: +1, Mass: 1, Location: nucleus.

Neutron details

Charge: 0, Mass: 1, Location: nucleus.

Electron details

Charge: -1, Mass: ~0, Location: shells

Father of the periodic table

Dmitri Mendeleev

How was the periodic table created?

Dmitri Mendeleev arranged elements by increasing atomic mass and grouped similar properties.

What does each box on the periodic table show?

Element name, symbol, atomic number, atomic mass.

What is an atomic number?

Number of protons in an atom.

What is atomic mass?

Total number of protons and neutrons.

Patterns across the periodic table?

Atomic number and atomic mass increase from left to right.

How to find subatomic particles?

Protons = atomic number

Electrons = atomic number (neutral atom) Ion charge = difference between protons and electrons

What do Bohr diagrams show?

Arrangement of electrons in energy shells.

Steps to draw Bohr models?

1. Find atomic number

2. Draw nucleus (protons + neutrons)

3. Add electrons in shells (2, 8, 8)

4. Fill inner shells first

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