Transcript Introduction to Matter

Access to HE Diploma
 Pharmacy and Biomedical Science
 Introduction to Matter
 Lesson 5
Hand in homework
 Moles, Formulae and Equations workbook.
Assessment Criteria
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1.1 Define an element giving examples.
1.2 Write the names and symbols of the first 20 elements.
1.3 Describe and explain what some of the general physical properties of metals and non-metals are
1.4 Describe the relative position of metals, non-metals, groups and periods within the periodic table with examples.
2.1 Classify substances as elements or compounds from their names giving examples
2.2 Describe two differences between a compound and a mixture
3.1 Describe protons, neutrons and electrons in terms of their relative charges and relative masses.
3.2 Describe the distribution of mass and charge within an atom.
3.3 Describe the contribution of protons and neutrons to atomic nuclei in terms of atomic number and mass
number.
3.4 Deduce the electronic configurations of atoms up to z = 36 and ions, given the atomic number and charge,
limited to s and p blocks up to Z= 36.
4.1 Describe ionic bonding as the electrostatic attraction between two oppositely charged ions including dot and
cross diagrams.
4.2 Describe a covalent bond as a pair of electrons shared between two atoms
4.3 Write the formulae for some simple and some complex compounds
4.4 Describe and interpret and/or predict physical properties in terms of the types motion and arrangement of
particles (atoms, molecules and ions) and the forces between them, and the different types of bonding.
5.1 Describe an acid as a species that can donate a proton.
5.2 Describe a base as a species that can accept a proton
5.3 Describe the reaction of an acid typified by hydrochloric acid with metals, carbonates bases and alkalis and
interpret them using ionic equations to emphasise the role of H+(aq)
5.4 Write a balanced equation for the reaction between two elements and between an acid and a base
6.1 Construct balanced chemical equations, full and ionic
Review Activity
Draw a diagram (using dots or crosses) to show the
bonding in magnesium chloride. Include ALL the
electrons in each species and the charges present.
Review Activity
 (b) Carbon forms an oxide called Carbon Dioxide, CO2.
The bonding in Carbon Dioxide can be represented as:
 O=C=O
 Complete the diagram below for the CO2 molecule
using dots or crosses to represent electrons. Just show
all of the outer shell electrons.
O
C
O
Review Activity
Define an ionic bond
Define a covalent bond
Today’s Aim
 Appreciate that some compounds, e.g. oxides, can be
acidic or basic
Week 5
 5.1 Describe an acid as a species that can donate a
proton.
 5.2 Describe a base as a species that can accept a
proton
 5.3 Describe the reaction of an acid typified by
hydrochloric acid with metals, carbonates bases and
alkalis and interpret them using ionic equations to
emphasise the role of H+(aq)
 5.4 Write a balanced equation for the reaction
between two elements and between an acid and a
base
Week 5 Reading
 Access to Chemistry
 Alan Jones, Mike
Clement, Avril Higton
Elaine Goulding
 ISBN 0 -85404-564-3
Inside the atom
Pages 105 - 111
5.1 Describe an acid as a species that can donate a
proton.
Acid Definition
Any of a class of substances whose aqueous solutions are
characterized by a sour taste, the ability to turn blue litmus
red, and the ability to react with bases and certain metals
to form salts.
A substance that yields hydrogen ions when dissolved in
water.
A substance that can act as a proton donor.
A substance that can accept a pair of electrons to form a
covalent bond
5.2 Describe a base as a species that can
accept a proton
Definition of a base
Any of a class of compounds whose aqueous solutions are
characterized by a bitter taste, a slippery feel, the ability to
turn litmus blue, and the ability to react with acids to form
salts.
A substance that yields hydroxyl ions when dissolved in
water.
A substance that can act as a proton acceptor.
A substance that can donate a pair of electrons to form a
covalent bond.
Acids and Bases
 Acids have a pH of less than 7. Bases have a pH of
more than 7. When bases are dissolved in water,
they are known as alkalis.
 Salts are made when an acid reacts with a base,
carbonate or metal. The name of the salt formed
depends on the metal in the base and the acid
used. For example, salts made using hydrochloric
acid are called chlorides.
Acids
 Substances with a pH of less than 7 are acids. The
stronger the acid, the lower the pH number. Acids turn
blue litmus paper red. They turn universal indicator
red if they are strong, and orange or yellow if they are
weak.
Bases
 Substances that can react with acids and neutralise
them to make a salt and water are called bases. They
are usually metal oxides or metal hydroxides. For
example, copper oxide and sodium hydroxide are
bases.
Alkalis
 Bases that dissolve in water are called alkalis. Copper oxide
is not an alkali because it does not dissolve in water.
Sodium hydroxide is an alkali because it does dissolve in
water.
 Alkaline solutions have a pH of more than 7. The stronger
the alkali, the higher the pH number. Alkalis turn red
litmus paper blue. They turn universal indicator dark blue
or purple if they are strong, and blue-green if they are
weak
Neutral solutions
 Neutral solutions have a pH of 7. They do not change
the colour of litmus paper, but they turn universal
indicator green. Water is neutral.
5.3 Describe the reaction of an acid typified by
hydrochloric acid with metals, carbonates bases
and alkalis and interpret them using ionic equations
to emphasise the role of H+(aq)
 When acids react with bases, a salt and water are
made. This reaction is called neutralisation. In
general:
 acid + metal oxide → salt + water
 acid + metal hydroxide → salt + water
 Remember that most bases do not dissolve in water.
But if a base can dissolve in water, it is also called an
alkali.
Carbonates
 When acids react with carbonates, such as calcium
carbonate (found in chalk, limestone and marble), a salt,
water and carbon dioxide are made. In general:
 acid + metal carbonate → salt + water + carbon dioxide
 Notice that an extra product - carbon dioxide - is made. It
causes bubbling during the reaction, and can be detected
using limewater. You usually see this reaction if you study
the effects of acid rain on rocks and building materials
Reactive metals
 Acids will react with reactive metals, such as
magnesium and zinc, to make a salt and hydrogen. In
general:
 acid + metal → salt + hydrogen
 The hydrogen causes bubbling during the reaction, and
can be detected using a lighted splint. You usually see
this reaction if you study the reactivity series of metals.
Acids, alkalis and neutralisation
 When atoms or groups of atoms lose or gain electrons,
charged particles called ions are formed. Ions can be
either positively or negatively charged.
 For the Higher grades, you need to know which ions are
produced by acids, and which are produced by alkalis.
You will also need to know the ionic equation for
neutralisation.
Acids
 When acids dissolve in water they produce hydrogen
ions, H+. For example, looking at hydrochloric acid:
 HCl(aq) → H+(aq) + Cl-(aq)
 Remember that (aq) means the substance is in
solution
Alkalis
 When alkalis dissolve in water they produce hydroxide
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ions, OH-. For example, looking at sodium hydroxide:
NaOH(aq) → Na+(aq) + OH-(aq)
Ammonia is slightly different. This is the equation for
ammonia in solution:
NH3(aq) + H2O(l) → (aq) + OH-(aq)
Be careful to write OH- and not Oh-.
Neutralisation reaction
 When the H+ ions from an acid react with the OH-
ions from an alkali, a neutralisation reaction occurs to
form water. This is the equation for the reaction:
 H+(aq) + OH-(aq) → H2O(l)
 If you look at the equations above for sodium
hydroxide and hydrochloric acid, you will see that
there are Na+ ions and Cl- ions left over. These form
sodium chloride, NaCl.
Naming salts
 You need to be able to work out which particular salt is
made in a reaction. You may be asked to describe how
to make a salt.
 The name of a salt has two parts. The first part comes
from the metal in the base or carbonate, or the metal
itself if a reactive metal like magnesium or zinc is
used.
 The second part of the name comes from the acid used
to make it. The names of salts made from hydrochloric
acid end in -chloride, while the names of salts made
from sulfuric acid end in -sulfate.
5.4 Write a balanced equation for the reaction between two
elements and between an acid and a base
Metal
sodium
hydroxide
copper
oxide
sodium
hydroxide
zinc oxide
Acid
Salt
reacts with
hydrochloric acid
to make sodium chloride
reacts with
hydrochloric acid
to make copper chloride
reacts with
sulfuric acid
to make sodium sulfate
reacts with
sulfuric acid
to make zinc sulfate
1. A solution has a pH of 4 - what does this mean?
It is acidic.
It is neutral.
It is alkaline.
2. Which of the statements below is correct?
Bases are acids that dissolve in water.
Bases are alkalis that dissolve in water.
Alkalis are bases that dissolve in water.
3. A liquid has a pH of 7. What does this tell you about the liquid?
It is water.
It is sodium chloride solution.
It is neutral.
4.
Which salt is made when calcium carbonate reacts with hydrochloric acid?
sodium chloride
calcium chloride
calcium sulphate
5.
Which pair of substances will react together to make copper sulfate?
copper and sulfuric acid
copper oxide and sulfuric acid
copper oxide and hydrochloric acid
6.
Which is the correct order of methods for making a salt from an acid and an
insoluble base?
filtration ==> evaporation ==> neutralisation
neutralisation ==> evaporation ==> filtration
neutralisation ==> filtration ==> evaporation
Review Week 5
 5.1 Describe an acid as a species that can donate a
proton.
 5.2 Describe a base as a species that can accept a
proton
 5.3 Describe the reaction of an acid typified by
hydrochloric acid with metals, carbonates bases and
alkalis and interpret them using ionic equations to
emphasise the role of H+(aq)
 5.4 Write a balanced equation for the reaction between
two elements and between an acid and a base
Workbook
 Complete section 6c pages 71 - 72
Next Week
Access to Chemistry pages 51 - 73
 4.1 Describe ionic bonding as the electrostatic
attraction between two oppositely charged ions
including dot and cross diagrams.
 4.2 Describe a covalent bond as a pair of electrons
shared between two atoms
 4.3 Write the formulae for some simple and some
complex compounds
 4.4 Describe and interpret and/or predict physical
properties in terms of the types motion and
arrangement of particles (atoms, molecules and
ions) and the forces between them, and the different
types of bonding.