ATOM
Atom is the smallest particles which is indivisible.
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.
Structure of atom
SUBATOMIC PARTICLES
Proton Neutron
Electron
SIMILARITIES:
1)They are subatomic particles.
2)Proton and neutron have the same mass.
3)Proton and neutron are located in the nucleus
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
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.
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
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.
CALCULATION OF NUCLEON NUMBER Example 1:
The following information is regarding the subatomic particles of atom P:
proton number = 13neutron number = 14
What is the nucleon number of atom P?
Example 2
Oxygen atom has 8 number of protons and 8 number of neutron. The nucleon number of oxygen atom is _______.
Exercise 1
In the sodium atom nucleus has 11 number of protons and 12 number of neutron. So, the nucleon number is _____.
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?
Exercise
Atom
Number of
proton
Number of neutron
Nucleon
number
Number of
electron
P 8 8Q 24 12R 19 39S 20 20
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?
PROTON Symbol: pCharge: +1Relative mass: 1Location: in the nucleus
NEUTRON
Symbol: nCharge: 0Relative mass: 1Location: in the nucleus
ELECTRON Symbol: e Charge: -1 Relative mass: 1 (negligible)
1840 Location: surrounding the
nucleus in a certain orbit