Acids and Bases

Note by zesha257, updated more than 1 year ago
Created by zesha257 almost 8 years ago


NCEA Level One Science Note on Acids and Bases, created by zesha257 on 09/11/2013.

Resource summary

Page 1

Atomic number= number of protons

Mass number = number of protons plus neutrons

Electron arrangement: How the atoms are arranged in the shells of the atom

Shell: The orbits which hold the electrons

Electron arrangement for first 20 elements: 2,8,8,2

Isotopes are elements with different numbers of neutrons. The mass of different isotopes is different as more or less neutrons changes the mass of a atom.

Proton = positive charge

Neutron = no charge

Electron = negative charge

Ion: an atom or group of atoms that has lost or gained electrons

Link to moodle for revision:

Atoms form ions to become stable by having a full outer shell of electrons.

Positive ions: Ions with a positive charge have LOST electron/s

Negative ions: Ions that have GAINED electron/s

Ionic compounds: a compound made when positive ion/s attract and bind to negative ion/s

Ionic compounds are neutral compounds

Chemical reaction: When two reactants interact with each other and form products

Reactant: existing substances in a chemical reaction.

Products: New substances that are formed during chemical reactions.

Reactant particles must collide with one another with enough energy to break the bonds within the particles.

Reaction rate: The speed at which the chemical reaction occurs

Reaction rate can be measured by the rate at which the reactants are used up or the rate at which products are formed.

Increasing the SURFACE AREA will increase the reaction rate.Smaller pieces of reactant expose more surface area and more reaction particles, so there are more effective collisions

Effective collisions: collisions that happen with enough energy and in the correct position to form new substances.

Increasing CONCENTRATION of a reactant (acid) will increase the reaction rate.A higher concentration (more) reactant particles results in a greater number of effective collisions.

Increasing the TEMPERATURE of the reactants increases the reaction rate.The reactants are moving faster, thus have more kinetic energy. This results in a higher number of effective collisions.


Hydrochloric acid + calcium carbonate ~~> calcium chlodire + water + carbon dioxide

2HCl + CaCO3 ~~> CaCl2 + H2O + CO2

ACID + BASE (metal oxide or metal hydroxide) ~~> SALT + WATER

hydrochloric acid + sodium hydroxide ~~> sodium chloride + water

HCl + NaOH ~~> NaCl + H2O

Nitric acid + copper oxide ~~> copper nitrate + water

2HNO3 + CUO ~~> Cu(NO3)2 + H2O

sulfuric acid + sodium hydroxide ~~> sodium sulfate + water + carbon dioxde

H2SO4 + 2NaHCO3 ~~> Na2SO4 + 2H2O + 2CO2

Acid: a substance that forms an acidic solution. It releases H+ ions into water which dissolve to make the solution acidic.

Strong acids have a high concentration of H+ ions. Strong acids are corrosive.

Weak acids have a low concentration of H+ ions. Weak acids have a sour taste.

The closer the pH is to 0, the stronger the acid. The closer to 7 the pH is, the weaker the acid.

Adding more acid to an acidic solution will lower the pH closer to 0.

Adding a base to an acidic solution will increase the pH closer toward 14.

Adding water to an acidic solution will slowly increase the pH closer to 7.

Indicators: substances that change colour when exposed to either an acid or a base. It can help to determine whether a solution is acidic or basic.

Universal indicator turns red for a strong acid (pH of 0-2), orange for a medium strength acid (pH of 3-4) and yellow for weak acids (pH of 5-6)

Litmus paper (both blue or red) turns red in acidic solutions.

Universal indicator turns green when exposed to neutral substances like pure water (pH 7)

Base: a substance that forms a basic solution. It releases OH- ions into water which dissolve to make the solution basic

The closer the pH is to 14, the higher the strength of the base.

Strong bases have a high concentration of OH- ions. Strong bases eat away materials through chemical action.

Weak bases have a low concentration of OH- ions. Weak bases have a bitter taste.

Adding more base to a basic solution will increase the pH closer to 14

Adding an acid to a basic solution will decrease the pH closer to 0.

Adding water to a basic solution will slowly decrease the pH closer to 7.

Universal indicator turns light blue in weak bases ( pH of 8-10), dark blue in medium strength bases (pH of 10-11) and purple in strong bases ( pH of 12-14)

Litmus paper (both blue and red) will turn blue in basic solutions

Elements, Isotopes & Ions


Acids & Bases

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