Transcript Chemistry Revision

CHEMISTRY REVISION
WHAT DOES THE STANDARD SAY?
Aspects of acids and bases will be selected from:
 Atomic structure
 electron arrangement of atoms and monatomic ions of the first 20
elements (a periodic table will be provided)
 isotopes
 ionic bonding
 names and formulae of ionic compounds using a given table of ions.
 Proper ties
 acids release hydrogen ions in water
 reactions (of acids with bases) to form salts.
 pH and effects on indicators.
 Rates of reaction and par ticle theor y.
 Uses
 neutralisation
 carbon dioxide formation
 salt formation
Acids and bases are restricted to HCl, H 2 SO 4 , HNO 3 , metal oxides,
hydroxides, carbonates and hydrogen carbonates.
WHERE TO BEGIN
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Know the basics:
Key definitions (ion, isotope, element, compound etc).
Names/symbols of ions, elements and compounds
The general equations
The factors of rates of reactions
Where substances fit into the pH scale
Positive test for litmus and universal indicators (acid, bases,
neutral and strength).
CAN YOU NAME THESE IONS?
CAN YOU NAME THESE ELEMENTS?
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U
Pb
Cu
Fe
Au
Ag
Ti
K
P
Zn
I
 Na
CAN YOU NAME THESE COMPOUNDS?
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Ca(OH) 2
Al 2 O 3
PbCl 2
NH 4 NO 3
BaSO 4
CAN YOU DEFINE THE FOLLOWING TERMS?
Ion
A charged atom that has lost/gained electrons in
their outer shell
Isotope
At atom of the same element (same number of
electrons/protons) but with a different number of
neutrons
Element
a substance made up of only one type of atom
Valence electrons
electrons in an elements outer shell that can be
lost or gained
Compound
Two or more element chemically combined
ATOMIC STRUCTURE
 What are these two numbers and what do they tell us?
 24
Mg
12
Atomic number = number of protons
Mass number= Number of protons and neutrons
How many Protons, electrons, neutrons?
12 protons, 12 electrons, 12 neutrons
How will the electrons be arranged?
2,8,2
IONS AND ISOTOPES
 What does Al 3+ mean? What has happened to the atom?
 Aluminium is an Ion that has lost three electrons (from
its outer shell) to be come positively charged by three. It
has done this because it still has the original number of
protons (13) which are positively charged.
 What is the difference between 12 C and 13 C? What is one
way the atoms will be physically different? What charge
do isotopes have? Why?
 Carbon 12 has one less neutron than carbon 13. They will
have the same numbers of electrons and protons (making
the atoms neutral). Because of this extra neutron, carbon
13 will be heavier.
HOW DO IONIC COMPOUNDS FORM?
 What is needed to make an ionic compound?
 A metal and a non-metal atom
 What happens when calcium as an ion wants to lose two
electrons but chlorine (chloride) can only gain one electron?
 Two chloride ions will form and join with calcium
 What charge will this compound have? What will the chemical
formula be?
 Neutral, CaCl 2
 Give the correct formula for the following compounds:
 Calcium Hydroxide
Iron (ii) carbonate
 Aluminium Sulphate
Ammonium bi-carbonate
NCEA QUESTIONS- ION FORMATION
QUESTION ONE: IONS AND IONIC FORMULAE
(a) Explain why the ions formed by aluminium and sulphur have
a dif ferent charge.
In your answer you should:
• describe an ion
• describe the atomic structures of a aluminium ion and
a sulphide ion
• state the charge on the aluminium ion and the
sulphide ion
• explain the charges on both ions in terms of electron
arrangement and number of protons.
ISOTOPES
Nitrogen can exist in dif ferent forms call isotopes. Two of these
isotopes are Nitrogen 14 (14, 7) and Nitrogen 15 (15, 7).
Explain why Nitrogen 14 and 15 are both neutral atoms. In your
answer you should fully describe their atomic structure and
electron configuration. You should also describe how they will
be physically dif ferent.
IONIC BONDING
Element Z is between numbers 5 and 12 on the Periodic Table.
An atom of element Z forms an ion. This ion combines with the
Aluminium ion to form a neutral compound, Al 2 Z 3 .
Determine what element Z is and justify your answer.
In your answer you should:
• consider the ratio of Z ions to aluminium ions
• use the formula Al 2 Z 3 to determine the charge of the Z ion
• explain how you would use the Periodic Table in your
Resource Booklet to find out which group element Z is in
• name element Z.