4. o All matter is made up of
small particles called atoms.
o Atom is the smallest particle
which can engage in a
chemical reaction.
o All the atoms of an element
have the same properties.
o Atoms of different elements
have different characters.
o atoms can neither be
created nor destroyed.
o Atoms are indivisivble.
5.
6. o Electrons carrying negative
charge.
o Mass of an electron is
1/1837 of themes of the
smallest atom - hydrogen
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9. Atom has a central part called nucleus.
Nucleus has positive charge
The mass of atom is concentrated in the
nucleus.
Electrons are distributed in the space around
the nucleus.
11. In Neil’s Bohr atom model
each of the orbit is a
specific energy level.
The energy levels 1, 2, 3,
4 and 5 are represented
by the letters K, L, M, N,
and O respectively.
These energy levels are
known as shells
12.
13.
14.
15.
16. Number of Protons in an atom is the atomic
number of the elements.
Mass Number is the total number of protons
and neutrons.
The maximum number of electrons that a shell
can contain can found out using the formula‘2 ’
