SNC1W Unit 1

What are the 6 main ideas of the Particle Theory of Matter?

1. All matter is made of tiny particles; 2. Particles of a pure substance are identical; 3. There are spaces between particles; 4. Particles are always moving; 5. Particles move faster when heated; 6. Particles attract each other.

How does the particle theory explain solids?

Particles are tightly packed, vibrate in place, and have strong attractions.

How does the particle theory explain liquids?

Particles are close together but can slide past each other.

How does the particle theory explain gases?

Particles are far apart, move freely, and have very weak attractions.

Which state of matter has a definite shape and volume?

Solid.

Which state has a definite volume but no definite shape?

Liquid.

Which state has neither a definite shape nor volume?

Gas.

What happens to particles when a substance is heated?

They move faster and spread farther apart.

What is a physical property?

A characteristic that can be observed without changing the substance.

Examples of physical properties

Colour, mass, volume, density, melting point, boiling point, texture.

What is a chemical property?

A characteristic that describes how a substance reacts to form new substances.

Examples of chemical properties

Flammability, reactivity, rusting, toxicity.

What is a qualitative property?

A property described using words instead of numbers.

Examples of qualitative properties

Colour, smell, texture, shape.

What is a quantitative property?

A property measured with numbers.

Examples of quantitative properties

Mass, volume, temperature, density.

What is a physical change?

A change that does not create a new substance.

Examples of physical changes

Melting ice, cutting paper, dissolving sugar.

What is a chemical change?

A change that creates one or more new substances.

Evidence of a chemical change

Colour change, gas produced, temperature change, light produced, precipitate forms, new odour.

Is melting a physical or chemical change?

Physical.

Is rusting a physical or chemical change?

Chemical.

How do you identify a physical change?

No new substance is formed.

How do you identify a chemical change?

A new substance is produced.

Properties used to describe substances

Colour, texture, hardness, density, melting point, boiling point, conductivity, solubility.

What are the three subatomic particles?

Protons, neutrons, electrons.

Charge of a proton

+1 (positive).

Charge of a neutron

0 (neutral).

Charge of an electron

−1 (negative).

Where are protons located?

In the nucleus.

Where are neutrons located?

In the nucleus.

Where are electrons located?

In electron shells around the nucleus.

Who developed the solid sphere model?

John Dalton.

Who discovered the electron?

J.J. Thomson.

Who proposed the nuclear model?

Ernest Rutherford.

Who developed the Bohr model?

Niels Bohr.

Who developed the electron cloud model?

Erwin Schrödinger.

How is the periodic table arranged?

By increasing atomic number.

What is the atomic number?

The number of protons.

How many electrons are in a neutral atom?

The same number as protons.

Formula for neutrons

Mass number − atomic number.

What is the mass number?

Protons + neutrons.

Rows on the periodic table are called

Periods.

Columns on the periodic table are called

Groups (families).

What is in the nucleus of a Bohr-Rutherford diagram?

Protons and neutrons.

Where are electrons shown in a Bohr diagram?

In shells around the nucleus.

Maximum electrons in the first shell

2.

Maximum electrons in the second shell

8.

Maximum electrons in the third shell (Grade 9)

8.

What are valence electrons?

Electrons in the outermost shell.

Why are valence electrons important?

They determine how an element reacts.

Group 1 elements

Alkali metals (1 valence electron).

Group 2 elements

Alkaline earth metals (2 valence electrons).

Groups 3–12

Transition metals.

Group 17

Halogens (7 valence electrons).

Group 18

Noble gases (8 valence electrons, except helium has 2).

How do you predict valence electrons?

Group 1=1, Group 2=2, Group 13=3, Group 14=4, Group 15=5, Group 16=6, Group 17=7, Group 18=8 (helium=2).

What does a chemical formula show?

The types and numbers of atoms in a compound.

How many hydrogen atoms are in H₂O?

2.

How many oxygen atoms are in H₂O?

1.

How many atoms are in CO₂?

1 carbon, 2 oxygen.

How many atoms are in NaCl?

1 sodium, 1 chlorine.

How many oxygen atoms are in CaCO₃?

3.

How many hydrogen atoms are in C₆H₁₂O₆?

12.

What does a subscript tell you?

The number of atoms of the element immediately before it.

Atomic number = ?

Number of protons = number of electrons (in a neutral atom).

Mass number = ?

Protons + neutrons.

Neutrons = ?

Mass number − atomic number.