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P.1
ELEMENTS
Physical Properties
-- properties that can be measured without changing the chemical composition of the substance,
e.g. ___________, ___________, ___________, state, _______ point, and ________ point.
Chemical Properties
-- properties that describe its ability to form new substances.
Physical Change
-- a change in which no new substances are formed.
Chemical Change
-- a change in which the starting substances (___________) are changed in one or more new substance
(___________).
The Three States of Matter
___________, ___________and ___________ are known as the three states of matter.
The Ways the particles are arranged.
Solid state :
The particles are packed __________ in a fixed pattern. There are strong forces
holding them together. They can only _________about fixed positions.
Liquid state : The particles are still close together but are not in a fixed pattern. The forces
that hold them together are ____________than in a solid.
Gas state :
The particles are widely spread. They move about very quickly. There are
almost _______ forces holding them together.
Gas
Solid
Liquid
Evaporation
On the surface of the liquid, the particles with more energy will overcome the attraction of the
surrounding particles. They break away from the liquid and form a gas (vaporize). Even at the same
temperature, different liquids evaporate at different rates.
Boiling
Boiling point - the temperature at which the particles are trying to escape from the liquid so rapidly
that bubbles start to form inside the liquid.
Liquids with high b.p. have _________ attractive forces between their particles than liquids with lower
b.p.
Condensation
When a gas is cooled, the particles lose energy. The gas condenses to form a liquid.
Melting and Freezing
Melting point - the temperature at which the solids melts to form a liquid.
Substances with high (low) melting points have strong (weak) attractive forces between the particles.
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P.2
Atoms
-
tiny particles that everything is made of .(smallest part of an element)
possesses the properties of that element.
Element
- a substance which is made up of only one kind of atoms
- a substance that cannot be made into anything chemically simpler.
- 109 elements are known (94 elements obtained from natural)
Names and Symbol for Elements (see P.15 table2.5)
All elements can be classified as metals, non-metals, semi-metals
metals:
aluminium, calcium, ....etc.
non-metals: bomine, carbon, fluorine, ....etc,
(helium, neon, argon are called noble gases.)
semi-metals: boron and silicon.
Metals are conductors while non-metals are non-conductors.
**Do P.14 Classwork**
ATOMS
Atoms consist of smaller sub-atomic particles: ___________, ___________and ___________.
--------------------------------------------------------------------------------------------------------------------------Sub-atomic
symbol
position
relative
relative
particles
charge
mass
--------------------------------------------------------------------------------------------------------------------------Proton
p
the nucleus
Neutron
n
the nucleus
Electron
e
the nucleus
-------------------------------------------------------------------------------------------------------------------------Atomic Number (Z) - the number of protons in an atom of the element
- in a neutral atom, no. of ___________ = no. of ___________
- a change in atomic no. results in a different element.
(memorize table 4.2)
Mass Number
(A)
= no. of protons + no. of neutrons
( since mass of electrons is too small)
A
X
Z
** Do P.26 Classwork 1, 2**
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Isotopes
P.3
- atoms of a particular element with the same number of protons and electrons
but different number of neutrons, e.g. 1H , 2H, 3H. (see P.59 Fig. 4.15)
- have the same chemical properties.
- differ in a few physical properties such as density.
Relative Atomic Mass
- Atom are so small that it is difficult to weigh them. So the mass of a carbon atom 12 C
to be as exactly 12 units.
-
is chosen
The mass of an atom found by comparing it with the 12 C atom is called its relative atomic mass .
The relative atomic mass of an element is the average mass of its isotopes compared with an atom of
12C.
For example: chlorine has two isotopes 35Cl (75%) and 37Cl (25%).
Find the relative atomic mass of chlorine.
Method to calculate : The relative atomic mass of chlorine
=(35 x 75 + 37 x 25) /100
= 35.5
**Do P.29 Classwork**
Arrangement of Electrons in Atoms (see P.30 Fig. 3.14, 3.15)
- Electron move around the nucleus in orbits ( called ___________ )
- The electrons will first fill up the first shell (nearest to the nucleus)
which can hold up 2 electrons.Then the electrons will fill in the
2nd shell (8 electrons), 3rd shell (18 electrons), 4th shell (32 electrons)
- The maximum number of e- held in each shell = 2n2 where n is the shell number.
- The arrangement of electrons in different shells is called the ____________ _________.
- Memorize P.31 Table 3.5. Note the case of potassium (2,8,8,1 but not 2,8,9)
calcium (2,8,8,2 but not 2,8,10)
** the electronic arrangement of an atom can also be represented by an electron diagram.
(see Fig 3.16)
e.g.
**Do P.32 Classwork**
Simple Ions
- note that helium (2), neon (2,8), argon (2,8,8)
Krypton (2,8,18,8), Xenon (2,8,18,18,8),
Radon(2,8,18,32,18,8) are noble gases and chemically very stable.
Except helium, all atoms of noble gases have 8 electrons in the outermost shell. This
suggests that an octet of electrons (i.e. 8 electrons ) in the outermost shell gives a particles
great stability. Helium is also very stable since its outermost shell is completely filled.
- A simple ion is formed when an atom either loses or gains one or more electrons. It may be
either positive ion (cation) or negative ion (anion) (see Fig. 3.17, 3.18, 3.19 3.20 )
Na
Ca
e.g.
23
11
Na 
Cl
+
O
+
__ p
35
17
Cl  __ p
__ n
__ n
__ e
__ e
**Do P.34 Classwork & P.41 Q.7**
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P.4
The Periodic Table
- In the modern periodic table, all the elements are arranged in order of ___________ atomic number.
- 1.The group number of an element is equal to the number of outermost shell electrons of
its atoms. ** Group number = number of ____________________ **
2. Elements in the same vertical column (called group) have ___________chemical properties .
(Why ? The reason is : The chemical properties of an element depend on the number of
___________shell___________ of its atoms. It is these outermost shell
electrons that interact during any chemical reaction. Since elements in the
same group have the same number of outermost shell electrons in their atoms,
their chemical properties are similar.)
3. As you go down a group, the physical properties change gradually .
- 1. Atoms of elements in the same period have the same number of shells of electrons.
** Period number = number of ______________________shells **
2. As you go across a period, the elements change from reactive ___________ on the left to reactive
___________ on the right.
3. The oxides of the elements in the period change from ___________ to ___________ in nature
from
left to right.
-
Special names of some groups :
Group I
--- ___________ metals
Group II --- ___________ ___________ metals
Group VII --- ___________
Group 0 --- ___________ ___________
**Do P.50 Classwork 1, 2**
Patterns Across the Periodic Table
Physical Properties
** Across a period, the elements change from ________ through ____________ to _________.**
Chemical Properties
The oxides of the period 3 elements change from ___________ to ________ in nature from left to right.
Group I Elements (Alkali metals)
Electronic Arrangement : 3Li (2,1) , 11Na (2,8,1) , 19K (2,8,8,1) , ........etc.
Electronic diagrams :
Similarities of Alkali Metals
1. All are reactive metals.(stored under oil)
2. All form ions with single +ve charge
(e.g. Li+, Na+, K+)
3. All form compounds with similar formulae
(e.g. LiCl, NaCl, KCl)
4. All react with non-metal to form salts which
are white, crystalline, and soluble.
5. All are soft and can be cut with a knife.
6. All have low density and low m.p. (b.p.).
**Do P.52 Classwork**
Difference in Reactivity of Alkali Metals
1. Their reactivity increases down the group.
Li
Na
K
|
|
|
|
|
Increase
In
Reactivity
2. The m.p. (b.p.) decrease down the group.
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P.5
Group II Elements (Alkaline Earth Metals)
Electronic Arrangement : 4Be (2,2), 12Mg (2,8,2), 20Ca (2,8,8,2), .......etc.
Electronic diagram :
Physical Properties.
- m.p. and b.p. are lower than normal metals
- harder than Gp. I metals
- **their surface are dull because of the presence of a layer of oxide.**
Similarities of Alkaline Earth Metals
Earth Metals
1. All are reactive metals.
2. All form ions with two +ve charges
(e.g. Be2+, Mg2+, Ca2+ )
3. All form compounds with similar formulae
( e.g. BeCl2 , MgCl2 , CaCl2 )
4. All react with non-metals to form salts.
5. All have low density.
Group VII Elements ( Halogens)
Electronic Arrangement : 9F (2,7), 17Cl (2,8,7),
Electronic diagram :
Physical Properties
As moving down the group,
there is a gradual change in state,
intensity of colour, m.p. and b.p.
1. They are less reactive than Group I elements.
2. Their reactivity increases down the group
Be
|
Increase
|
Mg
|
In
|
Ca
|
Reactivity
35Br
(2,8,18,7), 53I (2,8,18,18,7) ...etc.
(pale yellow gas) F
(greenish yellow gas)
Cl
(reddish-brown liquid) Br
(Black solid)
I
Similarities of the Halogens
1. All are poisonous and smelly.
2. All are non-metals.
3. All form diatomic molecules
(e.g. Cl2, Br2, I2 )
4. All react with metals to form salts.
**Do P.55 Classwork**
Difference in Reactivity of Alkaline
|
|
|
|
Increase
In
m.p. & b.p.
Difference in Reactivity of the Halogens
F
|
Increase
Cl
|
In
Br
|
Reactivity
I
|