Science Second Year 24/25

Density definition

the relation between somethings mass and its volume

Density formula

density=mass/volume

Force definition

a push or a pull. if you push or pull an object then you are applying force

Force unit

Newtons (N)

Friction definition

when one object slides over another object, friction tries to stop the movement. The rougher the two surfaces are the more friction.

Atom definition

the smallest particle of an element that still has the porperties of an element

Subatomic particle definition

a particle found inside an atom

Proton definition

a positively charged subatomic particle found in the centre of the atom

Electron definition

a negatively charged subatomic particle found outside the nucleus in the electron cloud

Neutron definition

a neutrally charged subatomic particle found in the nucleus

Atomic Number definition

the number of protons in the nucleus of the given atom

mass number

number of protons + number of neutrons

Ions definition

a charged atom or group of atoms

1st group of periodic table

alkali metals

2nd group of periodic table

alkaline earth metals

7th group of periodic table

halogens

8th group of periodic table

noble gases

Examples Of Acids

Corrosive: Hydrochloric Acid (stomach) and Sulfuric Acid (household drain cleaners)
Non corrosive: citric acid (lemons) and carbonic acid (fizzy drinks)

Red

colour litmus turns when an acid is present

blue

colour litmus turns when a base is present

Corrosive definition

if an acid or base is able to destroy solid materials by a chemical reaction.

Examples Of Bases

Corrosive: sodium hydroxide (household cleaners)
Non-Corrosive: Ammonia (soil)

Examples Of Neutral substances

Water, sugar and salt

Indicator definition

a compound that shows by a means of colour change whether a substance is an acid or base

Alkali definition

a base that dissolves in water

Neutralisation definition

the reaction between an acid and base when you combine them (to cancel eachother out)

Examples Of Neutralisation

Toothpaste (base) neutralises the acids that damage your teeth
Vinegar (acid) is used to neutralise the sting of a wasp (base)

Titration definition

a laboratory method used to accurately measure the volume of acid needed to neutralise a specific volume of base

Acids

A group of reactive chemicals that are corrosive and have a pH below 7

Bases

A group of reactive chemicals that are caustic and have a pH above 7.

Alkaline

A basic substance dissolved into water.

pH scale

A scale that measures the concentration of acids & bases. Less than 7 is an acid, 7 is neutral, more than 7 is a base. it ranges from 0-14

Universal indicator

An indicator with a different colour for each pH value.

Titration

A process in which an acid is used to measure the concentration of a base by recording how much acid it takes to neutralize the base.

Hydrochloric acid

Common strong acid found in laboratory and in stomach acid.

Sodium Hydroxide

Common base found in laboratories, and oven cleaner.

Acid rain

rain is naturally slightly acidic. Acid rain is rainfall made so acidic by atmospheric pollution that it causes environmental harm to stuff like vegetation and fish