Chemistry Unit1 Glossary

Front 1

Atom

Back 1

The smaller part of an element; all of them consist of protons and electrons.

Front 2

Atomic Number

Back 2

The number of protons in an atom. This defines the atom.

Front 3

Mass Number (2pt)

Back 3

-The number of protons+neutrons.
-It is always bigger than the atomic number.

Front 4

Average Atomic Mass

Back 4

The atomic mass of and element which averages the mass numbers of all isotopes and natural atoms.

Front 5

Proton

Back 5

A subatomic particle that is positively charged found inside the nucleus.

Front 6

Electron (2pts)

Back 6

-A subatomic particle which is negatively charged.
-This coils around the nucleus of an atom in shells.

Front 7

Neutron

Back 7

A dense subatomic particle which has no electric charge and is found inside the nucleus.

Front 8

Electron Shells (2pts)

Back 8

-The orbits of electrons around the nucleus.
-The energy level is higher in the outer shells than the inside ones.

Front 9

Valency Electrons

Back 9

The electrons in the outer most shell of an atom.

Front 10

Element

Back 10

A substance that is made of only one type of atom.

Front 11

Compound

Back 11

A substance made when two or more different elements are bonded together chemically.

Front 12

Molecule

Back 12

A group of atoms of the same or different element are bonded together.

Front 13

Isotope

Back 13

Atoms that are from the same element but have different mass numbers; they have the same amount of protons but different amount of neutrons.

Front 14

Periodic Table

Back 14

The arrangement of elements in order of small to bigger atomic numbers.

Front 15

Periods

Back 15

All the elements in a row across in the periodic table

Front 16

Groups (3pts)

Back 16

-All the elements in a column in the periodic table.
-They have the same amount of valency electrons.
-These elements have similar chemical properties.

Front 17

Metals (5pts)

Back 17

-Conduct heat and electricity
-High melting/boiling points
-Malleable (can be bent)
-Ductile (can be stretched)
-Shiny

Front 18

Metalloids (3pts)

Back 18

-Semi-conductors of heat and electricity
-Brittle (easily break)
-Shiny

Hint 18

B[Boron], Si[Silicon], Ge[Germanium], As[Arsenic], Sb[Antimony], Te[Tellurium], Po[Polonium]

Front 19

Non-metals (4pts)

Back 19

-Not a good conductor of heat and electricity
-Mostly gases
-Not shiny
-Low density

Front 20

Diffusion

Back 20

The process where particles move from high concentration to a lower concentration.

Front 21

Chemical Change

Back 21

A change in which a new substance is generated and is not reversible.

Front 22

Activation Energy

Back 22

The energy needed to start off a chemical reaction.

Front 23

Physical Change

Back 23

A change in which no new substance is made and it is reversible.

Front 24

Three states of Matter

Back 24

Gas, Liquid, Solid

Front 25

Gas (5pts)

Back 25

-Take the shape of a container
-Can be compressed
-Low concentration
-Particles are far from each other, and move randomly and swiftly
-No set order

Front 26

Liquid (4pts)

Back 26

-Take the shape of a container
-Can be poured
-Cannot be easily compressed
-Particles are close to each other but can move freely

Front 27

Solid (4pts)

Back 27

-Have their own shape
-Cannot be compressed
-High concentration
-Particles are very close to each other and vibrate

Front 28

Endothermic

Back 28

Changes of state that take in temperature; heat energy.

Front 29

Exothermic

Back 29

Changes of state that gives out temperature; heat energy.

Front 30

Freezing

Back 30

Liquid→Solid
Exothermic

Front 31

Condensation

Back 31

Gas→Liquid
Exothermic

Front 32

Sublimation

Back 32

Gas↔Solid

Front 33

Evaporation

Back 33

Liquid→Gas
Endothermic

Front 34

Melting

Back 34

Solid→Liquid
Endothermic

Front 35

Density

Back 35

How there are more/less particles in a particular volume when compared between the same substance.

Front 36

Law of Conservation of Mass (2pts)
Hint :)

Back 36

-Mass is not created nor destroyed by chemical reaction
-The total mass of reactants equals the mass of the products

Hint 36

Apply for Chemical Reactions

Front 37

Kinetic Molecular Theory (3pts)
Hint :)

Back 37

-Molecules never stop moving
-At higher temperature molecules move faster
-Temperature is a measure of speed with which molecules move

Hint 37

Apply for Physical Reactions

Front 38

Anion

Back 38

Negatively charged ion

Front 39

Cation

Back 39

Positively charged ion

Front 40

Combustion

Back 40

Reaction when a substance is burn in presence of oxygen, giving out heat energy

Front 41

Conservation of Mass

Back 41

The mass of the reactants in a reaction is the same as the products

Front 42

Equation

Back 42

A shorthand way to show the changes that take place in a chemical reaction

Front 43

Formula

Back 43

Combination of symbols that stand for proportions of elements in molecules and/or compounds

Front 44

Ion

Back 44

An electrically charged atom produced by loss or gain of electrons

Front 45

Lattice

Back 45

A giant 3D network of atoms or ions

Front 46

Precipitate

Back 46

An insoluble substance formed by a reaction taking place in solution

Front 47

Reaction

Back 47

A chemical change that makes a new substance(s)

Front 48

Soluble

Back 48

A substance that can be dissolved in a solvent

Front 49

Transition Metal

Back 49

Elements found in the central block of the periodic table which have metal properties and form coloured compounds

Front 50

Halogens

Back 50

Another name for group 7

Front 51

Noble gases

Back 51

The elements in group 0 which have a full outer shell of electrons and do not react with other elements

Front 52

Bohr Diagram

Back 52

A diagram used to show properties and structures of atoms