Unit 2: Matter and Chemical Change

Question 1

What is matter

Answer 1

• Anything that takes up space or has mass

- Can exist as a solid, liquid, gas or plasma

Question 2

What are some Physical Properties

Answer 2

Color, lustre, melting point, boiling point, hardness, conductivity, malleability, ductility

Question 3

What are some Chemical Properties

Answer 3

reaction with acids, ability to burn, reaction with water, behaviour in air, reaction to heat

Question 4

What is a pure substance

Answer 4

• Only one kind of matter and has unique properties

- An element is a material that cannot be broken down into any simpler substance.

Question 5

What are Mixtures

Answer 5

• substances held together by physical forces, not chemical.
• combination of pure substances.

Question 6

What is the difference between mechanical and mixtures and solutions

Answer 6

Mechanical (heterogeneous) mixture: the different substances that make up the mixture are visible.

Solution (homogeneous substance): the different substances that make it up are not separately visible.

Question 7

What is the difference between a suspension and a colloid

Answer 7

Suspension: a cloudy mixture in which tiny particles of one substance are held within another. These particles can be separated

Colloid: a cloudy mixture, but the particles of the suspended substance are so small that they cannot be easily separated out from the other substance

Question 8

What are some characteristics of Physical Changes

Answer 8

• change of state
• change in shape
• dissolving one substance in another
• reversible

Question 9

What was Democritus’s theory of matter

Answer 9

used atomos to describe the smallest particles of matter that could not be broken down any further.
Atomos means “indivisible”.

Question 10

What is Aristotle’s view on matter

Answer 10

Aristotle stated that everything was made up of EARTH, AIR, WATER and FIRE.
This view was held until about 1600 CE.

Question 11

Who were the alchemist

Answer 11

part magician and part scientist. Alchemy is a “pseudo-science”

They believed that is should be possible to change any metal into gold.

They invented many tools that are still used today such as beakers and filters.

Question 12

Who is Robert Boyle

Answer 12

1660
studied the properties of gases and believed that matter was made up of tiny particles.
believed these particles combined to make up different substances.

Question 13

Who is Antoine Lavoisier

Answer 13

1770’s
developed a system for naming chemicals.
defined substances such as hydrogen, oxygen and carbon.
“father of modern chemistry”.
One of the greatest scientists in France,
he executed by Guillotine during the French Revolution.

Question 14

Who is John Dalton

Answer 14

1808
suggests that all matter is made up of elements and that elements are pure substances.
The first to suggest that each element is made of a particle called an atom.
Hypothesized that atoms were tiny solid spheres,
Sometimes called the “billiard ball model”.

Question 15

Who is JJ Thompson

Answer 15

1897
used a cathode ray tube to determine that the cathode rays were made of negatively charged particles (electrons).
able to show that these particles were much smaller than atoms.
described the “raisin bun model” of an atom where the electrons were stuck on the atom.

Question 16

Who is Ernest Rutherford

Answer 16

1911
projected positively charged particles through thin gold foil and established that the nucleus was very small and positively charged.
believed that the electrons were located outside the nucleus.

Question 17

Who is Niels Bohr

Answer 17

1922
suggests that electrons do not orbit randomly but that orbit in specific “shells” around the nucleus.
believed that electrons jumped between these shells as they lost or gained energy.
His model is still used in teaching atomic structure

Question 18

What is today’s model

Answer 18

Electron Cloud Model (1920’s)- an atom consists of a dense nucleus composed of protons and neutrons surrounded by electrons that exist in different clouds at the various energy levels.

Question 19

Who created the system for organizing elements

Answer 19

Russian chemist Dimitri Mendeleev

placed in specific places because of the way they look and act.
The periodic table has rows and columns and they each mean something different.

Question 20

What are the periods of a periodic table

Answer 20

the rows of the periodic table
All of the elements in the same period have the same number of atomic SHELLS.
Every element in the top row (the first period) has one shell for its electrons.
All of the elements in the second row (the second period) have two shells for their electrons.
At this time, the maximum number of shells is seven.

Question 21

What are the groups of the periodic table

Answer 21

a column in the periodic table
The groups are numbered from 1 – 18 and are usually referred to by the first element in the column and have very similar properties to that element.
The elements in a group have the same number of electrons in their outer shell.
Every element in the first column (group one) has one electron is its outer shell. Every element on the second column (group two) has two electrons in the outer shell.
This is true for groups 1, 2, 13-18.

Question 22

what are the most important groups of the periodic table

Answer 22

Group 1 – The Alkali Metals - These are the MOST reactive metals on the periodic table.
Group 2 – The Alkaline - Earth Metals - These are the second most reactive metals.
Group 17 – The Halogens - These are the most reactive non-metals.
Group 18 – The Noble Gases - These are the least reactive substances on the table.

Question 23

What are the parts of an atom

Answer 23

Protons are positively charged particles in the nucleus of the atom.
Neutrons are neutral particles in the nucleus of the atom.
Electrons are negatively charged particles that orbit around the nucleus.
In a neutral atom, the number protons and electrons are equal.
(A molecule is two or more atoms together.)

Question 24

How do you show a compound is an aqueous solution

Answer 24

(aq) as a subscript, like (g), (l) and (s)

Question 25

What are some characteristics of ionic compounds

Answer 25

high melting and boiling points, good electrical conductivity, distinct crystal shape and are solids at room temperature.

Question 26

What are some characteristics of molecular compounds

Answer 26

They are insulators with low melting and boiling points and can exist at all three states at room temperature.

Question 27

What is a chemical reaction

Answer 27

when two or more substances combine to form new substances.

The materials at the start of the reaction are reactants.
The materials produced are called products.

Question 28

What is the difference between an Endothermic and Exothermic reaction

Answer 28

A chemical reaction that releases heat is called an exothermic reaction.
A reaction that absorbs heat is called an endothermic reaction.

Question 29

Name and describe the three chemical changes involving oxygen

Answer 29

Combustion – oxygen reacts with a substance to form a new substance while giving off heat. Example – Fire.
Corrosion – slow chemical reaction involving oxygen in air reacting with a metal. Example - iron and O2 in air – rust.
Cellular Respiration – takes place in body cells. Food reacts with oxygen to produce energy, water, and CO2.

Question 30

What is the Law of Conservation of Mass

Answer 30

The Law of Conservation of Mass states that matter is not created or destroyed in a chemical reaction.

This only works in closed systems – systems in which no reactants or products are allowed to escape.
An open system is one in which some reactants or products may escape.

Question 31

What are the four factors that affect the rate of chemical change

Answer 31

Catalyst – present in the reactants but is consumed during the reaction.

Concentration – the greater the concentration of the reactants the faster the reaction.

Temperature – The more heat added to the reactants the faster the reaction will take place.

Surface Area – increasing the surface area of the reactants allows more of the area to react, therefore increasing the rate of reaction.