Devonshire 2006
Year 9 Atoms, the building blocks
of matter
School Certificate ANSWERS
1. D, the columns that run down the periodic table are called groups, the rows that run across the periodic
table are called periods.
2. A, elements are made up of only one type of atom.
Element
Molecule
Made of only one type of atom
e.g. Carbon is made of only
carbon atoms; Oxygen is made of
only oxygen atoms, O2
Two or more atoms chemically
bonded together.
Can be the same type of atoms
(element) or it can also be
different types of atoms
(compound).
e.g. O2 is oxygen gas, it is an
element and a molecule.
H2O is water, it is a compound
and a molecule
Compound
Two or more atoms chemically
bonded together.
Must be different types of atoms.
e.g. H2O is made of hydrogen and
oxygen atoms.
H2SO4 is sulfuric acid; it is made
of hydrogen, sulfur and oxygen
atoms.
3. C, elements are grouped in vertical groups based on their similar properties and chemical reactivity.
The noble gases are very similar as they are all inert (not very chemically reactive) however there are other
very reactive gases such as fluorine, oxygen and chlorine.
Elements across the same row (period) are vastly different ranging from active metals on the left side
through to reactive gases and then the noble gases on the right side.
The elements arranged from atomic number 1 through to 20 again vary greatly as they are spread across the
periodic table.
4. D, atoms are chemically reactive because they have incomplete electron shells; they need to lose or gain
electrons by transferring or sharing electrons with other atoms that need to lose or gain electrons. We call
this electron transfer or sharing a chemical reaction. Atoms that have full electron shells do not need to gain
or lose electrons and are therefore said to be chemically inactive. The noble gases all have full electron
shells.
5. D, the most obvious difference on these diagrams is the way the particles (atoms) are held together. In the
diagrams the small black and white circles are supposed to represent two different types of atoms. The size
of each type of atom is the same in each diagram, the shape of the atoms is circular in each diagram and the
distance between them appears similar in both diagrams.
6. Look back at question two. The answer is an atom is the smallest unit that makes up an element.
7. A, it is showing an electron (the small circle) orbiting around a nucleus. In the picture there are two
electrons shown in the first shell (orbit) and four electrons in the second shell. Electrons have a negative
electrical charge.
B shows a neutron, a neutral charge sub-atomic particle that makes up part of the nucleus of an atom.
C shows a proton, positively charged sub-atomic particle that makes up part of the nucleus of an atom.
Devonshire 2006
8. The term ‘most abundant’ means which component (from the key) has the largest segment on the sector
(pie) graph. A protractor would come in handy for this question because you could quickly measure the
angle of each segment to get the answer.
Using common sense though, the three largest segments are the bottom three on the graph. Checking the key
reveals that only one of these three is an answer you can pick. C is the correct answer.
9. D, water is a compound (go back and look at question two). Manganese, silicon and oxygen are all found
on the periodic table. Everything shown on the periodic table is an element.
10. C is the only answer you can pick. All the other answers have information not shown anywhere on the
graph or in the key.
11. Again, a protractor would make this easy. At a guess I would say that comparing the size of the iron
segment to a right angled piece would give me an angle somewhere between 30-400. If it was 36 degrees
then it would be 10% of the circle (3600 in a circle).
B is the answer.
12. Oxygen and silicon have about the same size segments in the sector graph. Aluminium and calcium have
much smaller segments in the sector graph. D shows a similar pattern in the column graphs.
13. A, metals can be found on the left hand side of the periodic table, so P and T are metals.
14. The noble gases are not chemically reactive and are located in the far right hand column of the periodic
table. So S is a noble gas and C is the answer.
15. In a normal (neutral) atom the number of protons in the nucleus is the same as the number of electron
orbiting the nucleus. There are 3 electrons shown so that means the black dots in the nucleus are protons
(there are 3 of these as well). The 4 white dots must therefore be protons and D is the correct answer.
16. C, there are 3 black dots (protons) and 4 white dots (neutrons), 7 in total.
17ai. You can’t guess this, you must use a periodic table. Element 52 is
17aii. Again you need to look this up.
17b.