SNC 1W1 - Grade 9 Chemistry Unit Review

These questions should act as a guide to help you study. It is suggested you: write out answers to these questions using your notes; try the suggested textbook questions, at least orally if not written; study! To really be prepared, review your notes thoroughly, and these questions. If you have studied well, you should know your notes well and be able to answer these questions from memory.

What defines matter?

Anything that takes up space and has mass.

What is the difference between a physical property and a chemical property?

Physical properties do not change composition (state, form), while chemical properties involve alterations resulting in new substances (burning, reactions).

Give an example of a physical change.

Shredding paper: No new substance formed.

List five clues that indicate a chemical reaction has occurred.

Gas formed, precipitate formed, color/odor change, heat/light produced, new substance formed.

What is the pH scale used for?

It measures the acidity or basicity of a solution.

What is the difference between qualitative and quantitative properties?

Qualitative properties can be observed with senses; quantitative properties can be measured and have numerical values.

Which groups in the periodic table contain the noble gases, alkali metals, and halogens?

Noble gases: Group 18, Alkali metals: Group 1, Halogens: Group 17.

Describe the location, charge, and weight of a proton

Protons are located inside the nucleus, they have a positive charge, and weigh one unit.

What is an ionic bond?

A type of chemical bond formed through the transfer of electrons from one atom to another. (metal + non-metal)

What is the role of valence electrons in chemical reactivity?

They influence the ability of an atom to bond with others; atoms with few valence electrons tend to lose them and become reactive.

How do you describe a homogeneous mixture?

A mixture where the components are uniformly distributed and only one phase is visible.

What is a compound?

A pure substance that can be broken down into two or more different substances.

State the difference between metals, non-metals, and metalloids.

Metals are typically conductive and malleable, non-metals are brittle and poor conductors, metalloids have properties of both.

What is a characteristic property of acids?

They have a pH less than 7.

What occurs during a neutralization reaction?

An acid and a base react to form water and a salt.

What is meant by conservation of mass in chemical reactions?

The total mass of reactants equals the total mass of products.

Provide an example of a compound. What elements does it contain?

Vinegar (CH3COOH) contains hydrogen (4), carbon (2), and oxygen (2).

How would you classify water (H2O)?

It is a molecular compound. (non-metal and non-metal)

Describe the reactivity of noble gases.

Noble gases are non-reactive due to having a full outermost energy level. (orbit)

What is produced in a decomposition reaction?

A single compound breaks down into two or more simpler products.

What is an example of a chemical change?

Toasting marshmallows results in a new substance and a color change.

List the steps to drawing a Bohr-Rutherford Diagram

1. Write the standard atomic notation

2. Draw the nucleus as a circle

3. Write the number of protons & neutrons inside the circle

4. Draw circles (orbits) around the nucleus and add dots to represent electrons - the first orbit can only hold 2 electrons, the second can hold 8, and the third can also hold 8.

5. Check that the number of protons is equal to the number of electrons.

Explain how the steps to drawing a Bohr-Rutherford diagram would change to make it an Ion.

1. Cation (positive charge - metal when it loses electrons): Don’t draw as many electrons - just get rid of enough to have a full outer shell. Then write the difference as a positive charge on the notation.

2. Anion (negative charge - non-metal when it gains electrons): Add enough electrons to fill the outer shell, then write the difference as a negative charge on the notation.

What type of charge do neutrons have?

Neutral/no charge

How are electrons charged?

Negative

Give an example of how the properties of matter help to determine an element or compound’s usefulness in human applications.

Properties such as melting point, boiling point, reactivity, and conductivity help identify the suitability of elements and compounds for specific applications, such as in construction materials or pharmaceuticals. For example, the bottom of frying pans are made of copper to conduct the heat to the food.

Choose an element or compound and describe one negative societal or environmental impact of its use.

Cobalt - exposure to too much cobalt can lead to an asthma-like allergy to the element, including symptoms like coughing, wheezing, and difficulty breathing.

State whether the following pure substance is an element or compound.

Clear, colourless liquid that can be split into 2 gases, each with different properties.

Compound - water (H2O)

State whether the following pure substance is an element or compound.

A yellow solid always has the same properties and cannot be broken down by any means.

Element - sulfur (S)

 State whether the following pure substance is an element or compound.

A colourless gas burns to produce carbon dioxide and water.

Compound - fuel like propane

Describe the location, charge, and weight of a neutron

Neutrons are located inside the nucleus, they have a neutral/no charge, and weigh one unit.

Describe the location, charge, and weight of an electron.

Electrons are located inside the nucleus, they have a positive charge, and weigh 1/2000 units.

Describe the difference between a mixture and solution

What is the difference between heterogeneous and homogeneous