Chemistry Definitions Grade 9

Question 1

What are Alkali Metals

Answer 1

Found in Group 1, they are soft, silver, grey metals that are reactive

Question 2

What are Alkaline Earth Metals

Answer 2

Found in Group 2, they are silver, grey, solids that are harder then Alkali Metals and less reactive

Question 3

Atom

Answer 3

An atom is a particle that has nucleus of protons and neutrons surrounded by electrons

Question 4

Atomic Number

Answer 4

A number on an element symbol that signifies how many protons there are in that element

Question 5

Atomic Mass number

Answer 5

A number on an element symbol that signifies the amount of protons and neutrons averaged

Question 6

Bohr

Answer 6

Bohr changed Rutherfords diagram by having electrons “Orbit” around the nucleus at set “Energy Levels,” in this idea electrons could not orbit between the Energy levels

Question 7

Chemical Change

Answer 7

A chemical change occurs when a substance combines with another substance to form a new substance

Question 8

Chemical Formula

Answer 8

An expression that shows the elements in a compound and the relative proportions of those elements.

Question 9

Chemical Property

Answer 9

Describes the “ability” of a substance to undergo a specific chemical change

Question 10

Chemical Symbol

Answer 10

A short form of chemical elements, usually from the Latin alphabet (ex. Cu, Copper)

Question 11

Compound

Answer 11

A pure substance containing 2 or more elements that are chemically joined, is not on the periodic table

Question 12

Covalent Bond

Answer 12

2 atoms are bonded by sharing an electron in one of its orbits

Question 13

Electron

Answer 13

A negatively charged subatomic particle that orbits nuclei

Question 14

Element

Answer 14

A substance whose atoms all have the same atomic number

Question 15

Group/Family

Answer 15

The columns on the periodic table that dictate how many valence electrons there are in an element, left-right, 1-18

Question 16

Halogens

Answer 16

The 6 elements in Group 17 halogens are the most reactive non-metals and are usually found as compounds not elements
(F and Cl are gasses, Br is a brown liquid, I is a violet solid, At is radioactive)

Question 17

Matter

Answer 17

Anything that has mass and takes up space

Question 18

Metalloids

Answer 18

Along the staircase line, they have properties of metals and non-metals, some conductive, some not

Question 19

Metals

Answer 19

On the left side of the periodic table they have a metallic lustre, conductive of electricity, solid, and ductile

Question 20

Molecule

Answer 20

A group of 2 or more atoms held together by a chemical bond

Question 21

Neutron

Answer 21

A subatomic particle with a neutral charge in the nucleus

Question 22

Noble Gases

Answer 22

Found in Group 18, they are odourless, colourless, stable, valence shell is full so does not need more electrons to become stable

Question 23

Non-metals

Answer 23

Found on the right side of the periodic table they are gases, powdery solids, brittle, dull and poor conductors of electricity(generally)

Question 24

Period

Answer 24

The rows of the periodic table they signify the amount of orbits/energy levels of an atom

Question 25

Periodic table

Answer 25

A table of elements arranged by atomic number, valence electrons and orbits

Question 26

Physical change

Answer 26

The particles in the substance remain unchanged and the number of particles remain unchanged

Question 27

Physical Property

Answer 27

A characteristic of a substance that can be observed without changing the substance

Question 28

Proton

Answer 28

A positively charged subatomic particle that is found in the nucleus of an atom

Question 29

Pure substance

Answer 29

A substance where all molecules are exactly the same

Question 30

Rutherford

Answer 30

Realized positive charge was localized in the nucleus of an atom, but did not explain why electrons remain in orbit around the nucleus

Question 31

Standard atomic notation

Answer 31

An easier method to write an element with all necessary information, N and P combined top left, Atomic symbol middle, Protons/Electrons bottom left

Question 32

Subscript

Answer 32

A number written in the lower right corner behind the symbol of an element, used to indicate the number of atoms of any given element

Question 33

Valence electrons

Answer 33

The electrons in the furthest orbit from the nucleus

Question 34

Valence shell

Answer 34

The furthest orbit with electrons from the nucleus