Download Science 2nd prep. 1st term Atomic construction of Matter ** Matter

Science 2nd prep. 1st term
Atomic construction of Matter
** Matter consists of Molecules
** Molectules consists of Atoms.
The atom
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It is the fundamental building of matter
It is the smallest part of an element that can take part in a chemical reaction
without being changed
Note
Atomic radius of an atom is measured by unit called Angestrom which equal part of ten
thousands million of meter.
The chemical symbols of elements
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The symbol of any element is represented by symbol of the atom , it my be one
letter or two letters
The first letter should be a CAPITAL letter, while second letter should be a small
letter
The element
Symbol
The element
Symbol
Lithium
Sodium
Potassium
Hydrogen
Silver
Fluorine
Chlorine
Bromine
Gold
Helium
Li
Na
K
H
Ag
F
Cl
Br
Au
He
Oxygen
Calcium
Magnesium
Zinc
Load ‫رصاص‬
Aluminum
Silicon
Copper
Mercury
Iron
Carbon
Sulphur
O
Ca
Mg
Z
Pb
Al
Si
Cu
Hg
Fe
C
S
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Ms.Marim
Science 2nd prep. 1st term
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If two elements are similar in their initia‫ أ‬letters, so the second letter is taken to
differentiateْ between them, like:Carbon (C) and Calcium (Ca)
Sulphur(S) and silicon (Si)
Some symbols of elements are represented by the first and scond letter of Latin
name like:
Sodium (Natrium)=Na
Iron (Ferrum)=Fe
Copper (Cuprum)= Cu
Potassium (Kaluim)=K
The construction of the atom
It consists of 1-Nucleus 2- Electrons
1-Nucleus
 It is found at the center of the atom
 The mass of the atom is concentrated in it
 It contains two types of particles: Protons positively (+ve) charged particles
 Neutrons electrically neutral (±ve) particles
(uncharged)
Proton
Electron
Nucleus
Neutron
Energy level
Notice
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the number of neutrons my be equal to or greater than the number of protons
the nucleus is positively charged because it contains positive protons and
neutral neutron
2- Electrons
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1- Electrons are very minute particles and they are negatively (-ve) charged particles
2- The electron has a negligible mass relative to that of the proton or neutron, So
the mass of atom is concentrated in the nucleus
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3- Electrons orbit (revolve around the nucleus) with very high speed,
So they don't fall into the nucleus
These orbits (shells) are called "Energy levels"
2
Ms.Marim
Science 2nd prep. 1st term
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4- The number of negative electrons = the number of positive protons
So the atom is electricity neutral in the ordinary state
Comparison between the constituents of the atom :
Point of
comparison
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Proton

Neutron
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Electron
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1-position
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In the nucleus
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In the nucleus
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Around the nucleus
in the energy levels
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2- charge

positive(+ve)
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neutral (±ve)
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negative (-ve)
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3 Mass
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Greater than
electron mass
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Greater than
electron mass
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Very small
compared with
proton or neutron
mass
The atomic number
it is the number the positive protons in the nucleus of
an atom. And equal number the electrons which run
about it and The number writes under the symbol
The atomic mass

it is the sum number of the Protons and neutrons in the nucleus
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The atomic number= № of protons=№of electrons
The atomic mass= №of protons (atomic no.) +№of neutrons
Number of neutron =mass №– Atomic №
The elements
Mass number
Atomic number
The protons
The neutrons
7N
14
14
7
7
14-7=7
20Ca
40
40
20
20
40-20=20
13Al
27
27
13
13
27-13=14
17Cl
35
35
17
17
35-17=18
Problem
If the nucleus of oxygen atom contains 8 protons and 8 neutrons, find the atomic numbe
and the mass number of oxygen and how the xymbol of oxygen element is written??
3
Ms.Marim
Science 2nd prep. 1st term
The atomic number = 8
The mass number = 8 + 8 = 16
The symbol of oxygen element is
Complete the following table??
1
The elements
1H
Mass number
Atomic number
The protons
The neutrons
16
8
O
12Mg
24
11Na
23
12
6C
What is the meaning by
1- The Atomic number of magnesium equals 12
This means that the number of protons in the nucleus of magnesium atom equals 12
2- The Mass number of magnesium equals 24
This means that the sum of the number of protons and neutrons in the nucleus of
magnesium atom equals 24
☼The movement of electrons around the nucleus☼
Activity >>To imagine the movement of electrons around the nucleus
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steps
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Observation
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Conclusion
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1- Look at a turned
of electric fan.
2- Turn on the fan
to make it rotate.
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1- we can see the arms
of the fan clearly
2- The arms seen as a
cloud around the
center of the fan.
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The electrons revolve
around the nucleus in a
number of shells (orbits)
called "Energy levels"
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Level order
nucleus
Level symbol
4
Ms.Marim
Science 2nd prep. 1st term
Energy levels
1-They are imaginary regions in which electrons move according to their energy
2-Each energy level has its own energy
3-The maximum number of energy levels is 7(seven) levels
Level symbol
Level number(n)
K
1
L
2
M
3
N
4
O
5
P
6
Q
7
4-Each energy level can take a definite number of electrons this number can be
calculated from the relation (2n2) where (n) is the number of the energy level.
Examples
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The
The
The
The
no.
no.
no.
no.
of electrons in 1st level (K) =2× (1)2 =2 electrons
of electrons in 2nd level (L) =2× (2)2 =8 electrons
of electrons in 3rd level (M) =2× (3)2 =18 electrons
of electrons in 4th level (N) =2× (4)2 =32 electrons
5-the outermost energy level of any atom can't take more than 8 electrons except "K"
level which can't take more than 2 electrons
6- The rule (2n2) is not applied to calculate the number of electrons of the energy levels
higher than four because the atom become not stable
7-the energy of level increases as we go further from the nucleus, so the first level (K)
has the least energy, the seventh level (Q) has the highest energy
8- The electron is not transferred from one level to higher one unless gains some
energy equal that the different between the energy of the two levels,
which is known as Quantum the atom will be in excited stated. If the atom loses this
energy, it turns to it originals state known as ground state.
Quantum
It is the amount of energy gained or lost for the electron to transfer from an energy level
to another
The excited atom
It is the atom that gains quantum of energy.
5
Ms.Marim
Science 2nd prep. 1st term
Notice
- When an electron transfers from an energy level near the nucleus to higher one, it
gain a quantum of energy
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But when an electron transfers from an energy level near the nucleus to higher one,
it gain a quantum of energy
Electronic configuration
Atom of Symbol Atomic Atomic Structure of the
number mass atom
element
Hydrogen
Helium
Lithium
Carbon
Nitrogen
1
1H
4
2He
3Li
7
12
6C
14
7N
1
2
3
6
7
1
4
4
12
14
Electronic
configuration
No. of protons=1
No. of neutrons=0
No. of electrons=1
1p
No. of protons=2
No. of neutrons=2
No. of electrons=2
2p
2n
No. of protons=3
No. of neutrons=4
No. of electrons=3
3p
4n
No. of protons=6
No. of neutrons=6
No. of electrons=6
6p
6n
No. of protons=7
No. of neutrons=7
No. of electrons=7
7p
7n
n
Oxygen
16
8O
No. of protons=8
No. of neutrons=8
No. of electrons=8
6
8p
8n
Ms.Marim
Science 2nd prep. 1st term
Sodium
Magnesium
Chlorine
23
11Na
24
12Mg
17Cl
35
11
12
17
12
12
18
No. of protons=11
No. of neutrons=12
No. of electrons=11
11p
12n
No. of protons=12
No. of neutrons=12
No. of electrons=12
12p
12p
No. of protons=17
No. of neutrons=18
No. of electrons=17
17p
18n
Electronic configuration and chemical activity
The chemical activity of the atom determine by the number of electrons in the
outermost level
comparison between active gases and inactive gases:
Active elements
The number of electrons in Less than 8 electrons
outermost level
The activity
participates in a chemical
reaction
Example
Active elements (unstable)
It can with another atom
forming a molecule to be a
stable state
Sodium 2,8,1
Chlorine 2,8,7
Oxygen 2,6
Inactive elements
Equal 8 electrons
(completely) except (He)
contains 2 electrons
Inactive elements (stable)
It can't under normal
conditions
Noble gaseous :- (Helium,2
Neon 2,8
Argon 2,8,8
Krypton, Xenon, Radon)
Why 1H1 can participates in a chemical reaction, while Neon 2Ne4 is not???
 Because Hydrogen 1H1 have 1 electron in outermost energy level, so it is an active
elements – but Neon 2Ne4 have 8 electrons in outermost energy level, so it is an
inactive elements
7
Ms.Marim
Science 2nd prep. 1st term
Questions on lesson
Complete the following statements:
1 – the smallest part of the element that can take eparrt in a chemical reactions is known as …………..
2 – the symbol of mercury atom is ……… , while that of carbon atom is ……………
3 – Au is the symbol of …………. Element , while Ag is the symbol of …………….. element.
4 – the mass number is the number of ……. And ……… which exist in th nucleus.
5 – the number of ………. In the nucleus of ana atom may be ewqual to or greater thn the number o
……….
6 – the number of neutrons = …… number - ……… number .
7 – the symbol of the second energy level is ……….., while that of the fifth one is ……..
8 – as we go further from the nucleus, the energy of the levels……………
9 – when an electron transfers from M level to N elvel , it ………….. a quantum of energy.
10 – the maximum number of electons that saturates a given energy level is obtained from the rule
………. Which is applied only on the first …………. Energy levels.
11 – the second energy level is saturated with ………… electrons, while the fouth one is saturated with
…………….. electrons.
12 – electrons of sodium atom
11Na
are distriutedin number of energy levels equals ……………
13 – the energy level L of caron atom 6C contains …………… electrons, while that of sulphur atom 16S
contains …………….. electrons.
14 – the outermost energy level of argon atom 18Ar has ………. Electrons so, it is considered from
………….. elements.
15 – Noble gases have 8 electrons in outermost energy level except ………….. which has …….
Electrons.
16 – Active elements should have ……..than 8 electons in their outermost energy levels, so they can
react chemically with another atom to produce a …………. In a stable state.
My wishes,
8
Ms.Marim