Day 3 - Elements

Today we wrote a quiz, #1-16 and all marks count.

Homework today is:

1.) Read pgs 43 - 47 and complete #1-5 on page 47

2.) Checking concepts Pg 51 #1-4, #6-13

3.) Read pages 52 - 57, 60 -61 and do questions #1-21 on page 63


A good reference to review what you have learned about elements can be found here.

Answers:


Reading Check Answers, p. 47
1. Unlike iron, sodium melts at a low temperature,
is soft, and is highly reactive in water.
2. Iron is strong and can be made stronger by
adding carbon.
3. Mercury is the only metal that is liquid at
room temperature.
4. Chlorine is added to water to kill bacteria.
Chlorine also combines with sodium to make
table salt.
5. Silver can be polished and moulded and is
both malleable and ductile, making it useful
for jewellery. Its conductivity makes it useful
in electronics.

PG 51


1. (a) An element is a substance made up of only
one type of atom. More precisely, all atoms
of the same element have the same number
of protons.
(b) There are about 92 naturally occurring
elements (about 115–120 elements in
total).
2. Chemical symbols allow scientists to communicate
about elements in a way that is understood
by scientists all over the world.
3. (a) Hydrogen, nitrogen, oxygen, fluorine
(b) Bromine, mercury
(c) Answers may vary. Sample answer: potassium,
carbon, phosphorus, sulphur, iodine.
(d) Answers may vary. Sample answer: lithium,
sodium, rubidium, cesium.
4. Any two of strontium, magnesium, copper
6. Hydrogen
7. Silver
8. Iron and carbon make steel. Other metals are
usually added in as well.
9. The atmosphere is about 21% oxygen.
10. Oxygen in our atmosphere was produced by
plants over the past 3 billion years.
11. Sodium metal reacts violently with water,
making it unsuitable for use in drinking
glasses.
12. Chlorine in swimming pools is effective at
killing bacteria and other pathogens in the
water.
13. Hydrogen makes up more than 90% of the
atoms in the universe.
14. Silicon combines with oxygen to make sand.



Checking Concepts Pg. 63

1. The periodic table is a chart that organizes the
elements according to their physical and
chemical properties.
2. Atomic number = number of protons in each
atom of the element
3. Atomic number
4. (a) 2
(b) 8
(c) 26
(d) 79
(e) 92
(f) 101
5. An atom of potassium
6. Atomic mass is the mass of an atom of an element.
7. Atomic mass units
8. Atomic mass generally increases from left to
right and from top to bottom through the
table.
9. (a) 6.9 amu
(b) 28.1 amu
(c) 55.8 amu
(d) 63.5 amu
(e) 200.6 amu
10. Lead
11. Ion charge is an electric charge that forms on
an atom when it gains or loses electrons.
12. An electron
13. (a) Positive
(b) Negative
14. These elements do not form ions.
15. The element is capable of forming an ion in
more than one way.
16. (a) 2+, 3+, and 4+
(b) 2+
17. Metals, non-metals, and metalloids
18. (a) Alkali metals, alkaline earth metals, halogens,
and noble gases
(b) Alkali metals and alkaline earth metals
(c) Halogens and noble gases
19. Any five of boron, silicon, germanium, arsenic,
antimony, tellurium, polonium, and astatine
20. Periods
21. Families or groups