The document discusses the structure of atoms. It describes the historical understanding of atoms from Dalton's theory that atoms cannot be created or destroyed to Rutherford's discovery of the nucleus and Bohr's model of the atom. The structure of the atom is explained including subatomic particles like protons, neutrons, and electrons. Protons are located in the nucleus and have a positive charge while neutrons are in the nucleus and have no charge. Electrons surround the nucleus and have a negative charge. The proton number and nucleon number are defined and examples of calculating these numbers are provided.

1. ATOMIC
STRUCTURE

2. ATOM
Atom is the smallest particles which is
indivisible.

3. Historical development of atom
JOHN DALTON
atom cannot be created or destroy
J.J THOMPSON
atoms have electron scattered inside it.
ERNEST RUTHERFORD
nucleus has positive charge
NIEL BOHR
his proposed, atom model based on the solar system.
JAMES CHADWICK
in nucleus, have neutron that has no charges.

4. Structure of atom

5. SUBATOMIC PARTICLES
Proton Neutron
Electron

6. SIMILARITIES:
1) They are subatomic particles.
2) Proton and neutron have the
same mass.
3) Proton and neutron are located
in the nucleus

7. Differences:
Particles/
properties
Proton Electron Neutron
Charge Positive Negative Neutral (no
charge)
Location In nucleus Around
nucleus
In nucleus
Relative
mass
1 1/1840 1
Motion Stationary Move
around
nucleus in a
fixed orbit
Stationary
Symbol p e n

8. Proton number
 Proton number is the number of
protons in an atom of an element.
 Elements can be differentiated by
referring to their proton number.

9. Nucleon number
 Nucleon number is a total number of
protons and neutrons in an atom of an
elements.
Nucleon number = number of protons +
number of neutron

10.  In a neutral atom, the proton number also
refers to the number of electrons in that
atom.
In neutral atom,
Proton number = number of
protons
= number of
electrons in a
neutral atom.

11. CALCULATION OF NUCLEON NUMBER
Example 1:
The following information is regarding the
subatomic particles of atom P:
proton number = 13
neutron number = 14
What is the nucleon number of atom P?

12. Example 2
Oxygen atom has 8 number of
protons and 8 number of
neutron. The nucleon number
of oxygen atom is _______.

13. Exercise 1
In the sodium atom nucleus
has 11 number of protons
and 12 number of neutron.
So, the nucleon number is
_____.

14. Exercise 2
The nucleon number of calcium
atom is 40. The proton number of
calcium atom is 20. How many the
neutrons number in the atom
calcium?

15. Exercise
Atom Number
of
proton
Number
of
neutron
Nucleon
number
Number
of
electron
P 8 8
Q 24 12
R 19 39
S 20 20

16. Question To Try
1) What is the name of the positive
particles of an atom?
2) Where are electrons located in an
atom?
3) If an element X has 9 protons and
10 neutrons, what is its nucleon
number? How many electrons are
there in X?

17. PROTON
Symbol: p
Charge: +1
Relative mass: 1
Location: in the
nucleus

18. NEUTRON
Symbol: n
Charge: 0
Relative mass: 1
Location: in the
nucleus

19. ELECTRON
 Symbol: e
 Charge: -1
 Relative mass: 1 (negligible)
1840
 Location: surrounding the
nucleus in a certain
orbit