Unit 1-Glossary Flashcards

1
Q

acid

A

An aqueous solution of a substance which has a pH less than 7. There is an excess of hydrogen ions, H+ in the solution.

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2
Q

alkali

A

An aqueous solution of a substance with a pH greater than 7 . There is an excess of hydroxide ions, OH- , in the solution.

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3
Q

alkali metals

A
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4
Q

Aqueous (aq)

A

Indicates that the substance has been dissolved in water.

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5
Q

atom

A

The smallest particle that can be obtained by chemical means. An atom consists of a nucleus containing protons and neutrons, surrounded by electrons

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6
Q

atomic number

A

The number of protons in the nucleus of the atom.

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7
Q

base

A

A compound which neutralises an acid to form a salt and water. Bases can be soluble or insoluble. Metal oxides and metal hydroxides are bases. Soluble bases form alkaline solutions

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8
Q

covalent bond

A

Formed when non-metal atoms join together by sharing electrons to achieve a full outer shell of electrons (electron arrangement the same as the nearest noble gas, group 0).

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9
Q

covalent compounds

A

A compound of non-metal atoms held together by covalent bonds.

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10
Q

Covalent network

A

A large structure of covalently bonded atoms.

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11
Q

Diatomic molecules

A

Contain two atoms. They can be elements e.g. Hydrogen, Oxygen, Nitrogen, Fluorine, Chlorine, Bromine and Iodine (H2,O2,N2,F2,Cl2,Br2,I2) or compounds e.g. hydrogen chloride, HCl

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12
Q

electrolysis

A

The process of breaking down of an ionic compound into its elements by the use of an electric current.

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13
Q

electron

A

A very small negatively-charged particle found in the space surrounding the nucleus of an atom.

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14
Q

Electron arrangement

A

The arrangement of electrons in shells (or energy levels) around the nucleus of an atom.

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15
Q

element

A

A substance containing only one kind of atom. It cannot be broken down further by chemical means.

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16
Q

endothermic

A

In an endothermic reaction, energy is taken in from the surroundings. There is a decrease in temperature.

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17
Q

exothermic

A

A reaction in which heat energy is released. There is a rise in temperature.

18
Q

groups

A

A vertical column in the periodic table

19
Q

halogens

A

A group of very reactive non-metal elements in Group 7 of the periodic table.

20
Q

Indicator

A

A substance which changes colour at a particular pH.

21
Q

ion

A

A charged particle formed by loss or gain of electrons. When atoms lose an electron they become a positive ion (usually metals). When they gain an electron they become a negative ion (usually a non-metal).

22
Q

ionic compound

A

An ionic compound occurs when a negative ion (an atom that has gained an electron) joins with a positive ion (an atom that has lost an electron). This is usually a metal/non-metal compound.

23
Q

Isomers

A

Compounds with the same molecular formula but with a different structural formula.

24
Q

isotopes

A

Atoms of the same element that have different numbers of neutrons (different mass number).

25
Q

lattice

A

A lattice is a regular grid-like arrangement of ions in a solid ionic compound.

26
Q

mass number

A

The number of protons plus the number of neutrons in the nucleus of the atom.

27
Q

Mixture

A

Two or more substances together, but not chemically joined. They can be separated by physical means, e.g. filtering or distillation.

28
Q

Mole

A

One mole of an element is its atomic mass expressed in grams.

29
Q

molecule

A

A group of atoms held together by covalent bonds.

30
Q

neutron

A

A particle that is found in the nucleus of an atom, has a mass of 1 amu but no charge.

31
Q

noble gases

A

The elements in Group 0/8 of the periodic table. They have a full outer shell of electrons and so are unreactive.

32
Q

Nucleus

A

Found at the centre of an atom, the nucleus contains protons and neutrons.

33
Q

periods

A

The horizontal rows of the periodic table.

34
Q

Periodic table

A

The table of elements set out in order of their atomic number.

35
Q

pH

A

The number indicating the acidity or alkalinity of a solution, on a continuous scale. pH less than 7 is acidic, pH 7 is neutral and greater than 7 is alkaline.

36
Q

Precipitate

A

The insoluble solid formed in a solution during a chemical reaction.

37
Q

relative atomic mass

A

The average mass of the atoms of an element.

38
Q

solute

A

The material that dissolves in a solvent to form a solution.

39
Q

solution

A

Formed when a solute dissolves in a solvent.

40
Q

solvent

A

The liquid in which the solute dissolves in to form a solution.