CHAPTER-03 STRUCTURE OF MATTER
Transcript of CHAPTER-03 STRUCTURE OF MATTER
CHAPTER-03
STRUCTURE OF MATTER
𝐙𝐀𝐗𝐦±
Expression Of Atom
Board Question 2019❖ 13
27Al3+ in this formula-
(i) Mass Number 27
(ii) Number of electrons 13
(iii) Number of neutrons 14
Which one is correct ?
(a) i, ii (b) i, iii (c) ii, iii (d) i, ii, iii
Poll Question-01
Expression Of Atom
❑ What is the actual mass of a proton ?
(a) 1.765 × 10−24g
(b) 1.75 × 10−24g
(c) 1.675 × 10−24g
(d) 1.673 × 10−24g
Board Question 2019
Isotope Isotone Isober
Structure Of Atom
Isotope → Equal number of protons
Isober → Equal mass number
Isotone → Equal number of neutrons
Relative Atomic Mass
❖ If the mass of an atom of a element is 2.66 × 10−23 g, what is the name of the
element? (Jessore Board -2020)
❖ Relative atomic mass = (Mass of one atom)
1/12 × C12
Average Relative Atomic Mass
𝐙𝐀𝟏𝐗 a%
𝐙𝐀𝟐𝐗 b%
𝐙𝐀𝟑𝐗 c%
Relative Atomic Mass
❖ In nature we get two isotopes of copper and they are 2963Cu and 29
65Cu respectively.
The average atomic mass of copper is 63.5 . Determine the percentage amount of
those isotopes.
Chattogram Board 2020(a) Define nucleon number.
(b) Why does relative atomic mass have not any unit ?
Relative Atomic Mass
The energy of the rotating electron radiates and
falls into the nucleus.
Rotating electrons
(i) Nucleus stays in the center of the atom, almost total mass of the atom is determined in nucleus.
(ii) Atom is charge-neutral. Equal number of protons and electrons stay in the atom.
(iii) The static electric attraction force between proton and electron acts like centripetal force and
because of this centripetal force electrons move round the nucleus like our earth does round the
sun.
Rutherford’s Atomic Model And Limitations
Bohr’s Atomic Model
1. Orbit of fixed energy
2. Angular momentum opinion-
mvr = nh
2π
3. Opinion for Electron shifting in orbits-
∆E = En2 − En1
Atomic Model
Event-1 : 1911 year (Chittagong Board -2020)
Event-2 : 1913 year
• Describe the importance of Event-1 in chemistry• Explain that- Event 2 is the corrected feature of Event-1
Orbit & Orbitals
Orbit Shell(n)
𝒍 = 𝒏 − 𝟏 Sub ShellNumber of Sub Shells
Number of
orbitals
Number of electrons in sub-shell= 𝟐(𝟐𝐥 + 𝟏)
Total number of electrons
K 𝐧 = 𝟏 𝐥 = 𝟎 𝟏𝐬 𝟏 1 𝟐 𝟐 × 𝟎 + 𝟏 = 𝟐 2
L 𝐧 = 𝟐𝐥 = 𝟎𝐥 = 𝟏
2s2p
2 13
𝟐 𝟐 × 𝟎 + 𝟏 = 𝟐𝟐 𝟐 × 𝟏 + 𝟏 = 𝟔 8
M 𝐧 = 𝟑𝐥 = 𝟎𝐥 = 𝟏𝐥 = 𝟐
3s3p3d
3135
𝟐 𝟐 × 𝟎 + 𝟏 = 𝟐𝟐 𝟐 × 𝟏 + 𝟏 = 𝟔𝟐 𝟐 × 𝟐 + 𝟏 = 𝟏𝟎
18
N𝐧 = 𝟒
Ca(20) =
Cu 29 =
Sc(21) =
Cr(24) =
Electronic Configuration
Chapter 04Periodic Table
Periodic Table
Periodic Table
Group 1 – Alkali Metals
Group 2 – Alkaline Earth Metals
Group 18 – Noble Gas
Group 17 – Halogen
Group 16 – Chalcogen
Name of Different Groups in Periodic Table
Determine The Position Of Element In The Periodic Table
Last
ElectronGroup Period
s The number of electrons of the last s Maximum no. of n
pThe number of electrons of p+ The
number of electrons of the last s + 10Maximum no. of n
dThe number of electrons of d+
The number of electrons of the last sMaximum no. of n
Periodic Table
A Si B S Cl
Dhaka Board 2020Portion of Periodic Table
[A & B are used here symbolically]
What is the period & group of ‘B’ element in the periodic table ?
(a) period-2, group-3
(b) period-3, group-15
(c) period-4, group-11
(d) period-6, group-12
Periodic Properties
1. Atomic Radius
2. Ionization Potential
3. Electron Affinity
4. Electro-Negativity
5. Metallic properties
❖ One energy shell is added when going downwards in a group .
Atomic Radius
Atomic Radius
In a period, from left to right electrons and protons increases though energy shell
remains the same.
𝐍𝐚 𝒈 𝐍𝐚+ 𝒈 + 𝒆−
Ionization Energy
𝐂𝐥 𝐠 + 𝐞− 𝐂𝐥− 𝐠
Electron Affinity
Electronegativity
Periodic Properties at a glance
Metals
Semimetals
Nonmetals
Electronegativity
Ionization Energy
Electron Affinity
Atomic Radius
Ion
izati
on
En
erg
y
Ele
ctr
on
eg
ati
vit
y
Ato
mic
Rad
ius
Ele
ctr
on
Aff
init
y
Solving Board Questions
Rajshahi Board 2020
❖ Among Na & Na+ which one’s size is smaller ? Explain.
Which one has the least ionization energy ?
(a) X (b) Y (c) E (d) G
Solving Board Questions
Answer the following questions :
Group → 1 2 17 18
Period 1 E
2 D
3 X Y G
Answer the following questions :
Group → 1 2 17 18
Period 1 E
2 D
3 X Y G
(i) Metallic property of Y is less than X
(ii) D is the most electronegative
(iii) Y can gain electronic configuration of G
Which one is correct ?
(a) i, ii (b) i, iii (c) ii, iii (d) i, ii, iii
Solving Board Questions
ElementElectron number in the last energy
level
A
B
C
D
𝟑𝐬𝟐
𝟐𝐬𝟐𝟐𝐩𝟒
𝟏𝐬𝟏
𝟐𝐬𝟐𝟐𝐩𝟓
Solving Board Questions
Determine the elements A, B, C & D [Board -2019]
LiNaCRb
Mg Al Si B AD
ClBrI
Solving Board Questions
• Explain the order of atomic size of A, B, C & D [Board -2016]
❖ Explain the order of atomic size of X,Y & Z [Board -2019]
Solving Board Questions
Element Electron number in the last energy level
X Has 2 protons less than Cl
Y Placed in 4 side right from Ca
Z Placed in period 4 and group 2
❖ Explain the order of atomic size of A, B & C . [Board 2018]
Element Period Group
A 2 14
B 2 17
C 3 2
Solving Board Questions
𝟗𝑷
𝟏𝟕𝑸
𝟏𝟗𝑿 𝟐𝟎𝒀 𝟐𝟏𝒁 𝟑𝟓𝑹
𝟓𝟑𝑺
Solving Board Questions
a) What is Dobereiner's law of triads ?
b) Why ‘Ar’ is called as inert element ? Explain.
c) Explain the order of atomic size from X to R.
d) Show with reactions that , “Elements of same group has same properties.”
[Dhaka Board -2020]