Unit 2: Chemistry

Question 1

Physical Change

Answer 1

A change that can be reversed and still has the same particles where no new substance is formed
Example: cutting paper, freezing H2O, melting butter

Question 2

Chemical Change

Answer 2

A Chemical change is a change in which a whole new substance is formed. For example, when you are baking cookies the baking soda when heated gas is released making the new substance fluffier and lighter. A chemical change cannot be reversed.
Example: sodium and water

Question 3

Qualitative

Answer 3

Properties that can only be described by words.
Example: colour, texture, and state of matter.

Question 4

Quantitative

Answer 4

Properties that can be defined by a precise measurement ( A numerical value)
Example: boiling point, mass, density.

Question 5

Homogenous mixture

Answer 5

can’t see different particles usually clear cannot be filtered to separate particles
Example: Windex

Question 6

Heterogeneous or mechanical mixture

Answer 6

not uniformly scattered you can see different particles
Example: cookies muffins

Question 7

Pure substances

Answer 7

only one type of particle
Example: sugar

Question 8

Element

Answer 8

more than 100 substances that cannot by ordinary chemical means be separated into different substances

Question 9

Proton

Answer 9

positively charged particle
found inside the atomic nucleus

Question 10

Neutron

Answer 10

uncharged particles in the
atomic nucleus

Question 11

Matter

Answer 11

anything that takes up space and can be weighed
example: volleyball

Question 12

Molecule

Answer 12

Smallest independent unit of pure substances. Generally, a cluster of atoms joined together
Example: Tightly joined together molecules is an atom

Question 13

Solution

Answer 13

A homogeneous mixture of 2 or more pure substances
Example: Brass made from copper and zinc

Question 14

Suspension vs Colloid

Answer 14

Suspension is when 2 heterogeneous mixtures mix in which particles settle

A colloid is between a solution and a fine suspension

Question 15

Scientific Law

Answer 15

Law is used to summarize an observation
Fore = Mass x Ecelleration

Question 16

Scientific theory

Answer 16

Theories are possible reasons why something acts the way it does
Example: Atom theory is matter is made up of tiny particles

Question 17

Cation

Answer 17

If an atom loses electrons it becomes positively charged and is called a cation

Question 18

Anion

Answer 18

if an atom gains electrons it becomes negatively charged and is called an anion
Example: K-

Question 19

Metal

Answer 19

Usually a solid shiny, conductive material
Example: brass

Question 20

Non-metal

Answer 20

An element or substance that is not metal; Liquid or gas
Example: helium

Question 21

Metalloid

Answer 21

Elements with properties in between metals and nonmetals

Question 22

Valence Electron

Answer 22

Electron that is on the outer shell of the atom. Controls the atom’s chemical properties.

Question 23

Ionic bond

Answer 23

Electrons transferred between a non-metal and metal are then attracted to each other because of the negative and positive charges.

Question 24

Covalent bonds

Answer 24

Electrons shared between 2 non-metals

Question 25

Diatomic molecule

Answer 25

molecules that when bonded with another of themselves they are more stable

Question 26

Compound

Answer 26

Pure substances That are made up of two or more elements bonded together

Question 27

Multivalent Ions

Answer 27

ion with more than one # of positive or negative ions

Question 28

Polyatomic ions

Answer 28

ions with more than one atom

Question 29

Chemical formula

Answer 29

tells us three things about the compound
1 how many atoms
2 which elements are present
3 what state of matter it’s in

Question 30

valence shell

Answer 30

outermost shell of an atom containing the valence electrons

Question 31

Products

Answer 31

the substances produced by
a chemical reaction

Question 32

Reactants

Answer 32

The substances that go into a chemical reaction

Question 33

Exothermic

Answer 33

Chemical reaction where heat energy is released to the surroundings

Question 34

Endothermic

Answer 34

Chemical reaction where heat energy is taken away from the surroundings

Question 35

Formation

Answer 35

2 separate elements combine to form a compound or 2 simple compounds combine to form a complex compound

Question 36

Decomposition

Answer 36

A compound separates into 2 elements or a complex compound separates into 2 simple compounds

Question 37

Single replacement

Answer 37

there is one element and one compound then the element switches places with another element in the compound

Question 38

Double replacement

Answer 38

there is 2 compounds and the two negatively charged ions switch places.

Question 39

Combustion

Answer 39

the highly exothermic
combination of a substance with
oxygen; requires heat, oxygen,
and fuel

Question 40

Catalyst

Answer 40

A substance that speeds up a chemical reaction, the substance isn’t used up. (eg: sodium solution in elephant toothpaste. )

Question 41

Enzyme

Answer 41

A type of catalyst that speeds up biological processes. Eg: Aylase:
enzyme that is in saliva, breaks down carbohydrates.