Glossary

Question 1

Chemistry

Answer 1

Study of elements and the compounds tehy form, and the reactions they undergo

Question 2

Matter/ Material

Answer 2

Gas, liquid, or solid.

Anything that has MASS / VOLUME

Question 3

Properties

Answer 3

Characteristics that give matter its unique identity

Question 4

Extensive Prop

Answer 4

A property that depends on the AMOUNT of the material in a sample such as MASS/ VOLUME

Question 5

Intensive prop

Answer 5

A property that is INDEPENDENT of the amount of the material in a sample such as DENSITY / COLOR

Question 6

Physical properties

Answer 6

properties that can be measured without changing the composition of a substance such as COLOR/ MELTING PT

Question 7

Chemical properties

Answer 7

properties that describe the composition and reactivity of a substance
i.e HOW IT CHANGES INTO OTHER SUBSTANCES

Question 8

Substance/ component

Answer 8

A single, distinct chemical species
i.e PURE MATERIAL, such as water and oxygen.
It has a composition that remains unchanged

Question 9

States of matter

Answer 9

the 3 forms in which matter cna be found ; solid, liquid/ gas

Question 10

Change of States

Answer 10

Transformations of matter from one state to another, such as from a liquid to a gas.
eg Boiling water= produces steam

Question 11

Mixture

Answer 11

Combination of 2 or more substances in which each substance retains its own chemical identity

Question 12

Element

Answer 12

A substance that cannot be separated into more simple substances by chemical . physical means such as Oxygen

Question 13

Compound

Answer 13

A substance composed of 2/ more elements combined chemically in FIXED PROPORTIONS and are classified as MOLECULAR (water, H2o) and NON MOLECULAR (sodium chloride NaCl)

Question 14

Homogenous mixture

Answer 14

Composition is uniform throughout.

I.e all mixture have the same INTENSIVE PROPERTIES, eg air/ sea water

Question 15

Heterogenous mixture

Answer 15

Composition is not uniform.

i.e intensive properties vary from place to place in mixture ( MILK/ ROCKS)

Question 16

Atom

Answer 16

The smallest unit of matter that retains the properties of an element

Question 17

Allotropes

Answer 17

Diff forms of the same element

i. e the FORMS have their atoms arranged differently .
eg. graphite and diamond = allotropes of carbon

Question 18

Chemical formula

Answer 18

Notation for a chemical COMPOUND using the chemical symbols for the elements presnet
eg. water - H2O b/c both elements hydrogen and oxygen are chemically combined in teh ratio of 2 hydrogens and one oxygen.

Question 19

Molecular Formula

Answer 19

A chemical formula that indicates the actual number of atoms of each element in one molecule OF a substance

Question 20

Empirical formula

Answer 20

A chemical formula that indicates the actual number of atoms and their relative numbers in a substance in the smallest possible WHOLE NUMBER RATIO
eg. Hydrogen Peroxide= MF H2O2, EF= HO
Ethylene= MF= C2H4, EF= CH2

Question 21

Subatomic particles

Answer 21

The central core of an atom that contains protons and neutrons

Question 22

Protons (p)

Answer 22

A positively charged subatomic particles present in the nucleus of an atom

Question 23

Electron (e)

Answer 23

A negatively charged subatomic particle present far outside the nucleus of an atom.
It has a mass 1/1836 times that of a proton

Question 24

Neutron

Answer 24

An electrically neutral particle present in the nucleus of teh atom.
Has approx. the same mass as a proton.
Diff numbers of neutrons in the nuclei of an element from isotopes of that element.

Question 25

Atomis Mass Units (MU)

Answer 25

A unit based on the value of 12 amu for the mass of the isotope of carbon (12C) that has 6 protons and 6 neutrons in the nucleus. Thus a proton and neutron have almost the same mass of 1 amu each, and an electron has a mass of 0.0005 amu

Question 26

Atomic number (Z)

Answer 26

The number of protons in the nucleus of an atom of an element. This number identifies a particular element for example Z= 30 must be zinc

Question 27

Mass Number (A)

Answer 27

The sum of the number of protons and neutrons in the nucleus of an atom of a particular isotope of an element.

Question 28

Atomic Symbol

Answer 28

Defines atom completely by utilising the chemical symbol X, of an element combine with A, Z eg..A/Z X

Question 29

Periodic table

Answer 29

The arrangement of the elements in the order of increasing atomic number with elements having similar properties placed in vertical columns

Question 30

Metals

Answer 30

Represet 4/5 of the elements in teh PT, and are solids at room temp(expt mercury) Metals have LUSTER, MELLEABILITY, DUCTILITY and good THERMAL and ELECTRICAL CONDUCTIVITY. eg. Sn. Fe, Zn

Question 31

Non metals

Answer 31

Represent 1/5 of teh elements in the PT and teh majority 2/3 are gaseous and the remaining 1/3 are solids (METTALOIDS) Most of these elemenst are POOR CONDUCTORS of heat & electricity. H/w Metalloids or semiconductors have properties intermediate btw those of metals an non metals

Question 32

Inert gases

Answer 32

composed of the 6 elements; He, Ne, Ar, Kr. Xe, Rn and occupy the last column of the PT. All these elements are very nonreactive , all are gases at room temp and exist as individual atoms

Question 33

Molecules

Answer 33

2/ more atoms held together by chemical bonds. All the remaining nonmetals , 1.e not including metalloids and the inert gases, exist as molecules. eg. N2 , O2, Cl2, P4, S8

Question 34

Ion

Answer 34

An electrically charged atom or group of atoms (polyatomic ions) Ions can be positively/ negatively charged depending on whether electrons are lost (positive) / gained (negative ) by the atoms

Question 35

cation

Answer 35

An ion with a positive charge, formed by the loss of one or more electrons; such as Na+, Ca+, NH+4

Question 36

Anion

Answer 36

A negatively charged ion formed by the gain of one or more electrons; sucj as Cl0, O2-, No -3