Download Unit 2 Topic 1

The Atom
Unit 2 Topic 1
Subatomic Particles
The smallest particle of an element that
still has the properties of that element is the
atom.
Atoms are made up of subatomic particles
called Protons, Neutrons, and Electrons.
Atoms of the same element have the same
number of protons and atoms of different
elements have a different number of protons.
Protons continued
Therefore we use the number of protons
to identify an element and call this the
atomic number of the element.
The subatomic particles differ in their
mass, charge, and relative position
within the atom.
Charge, Mass & Location
Particle
Charge
Mass
Location
Proton
+1
1 amu
Nucleus
Neutron
0
1 amu
Nucleus
Electron
-1
0 amu
Outside
the
nucleus
Protons, Neutrons & Electrons
# Protons
If neutral then also # electrons
Atomic weight – protons =
Neutrons
Shape
An atom is basically spherical in shape
with a dense positively charged nucleus
containing the protons and neutrons
The nucleus is surrounded by electron
clouds, which are at specific distances
from the nucleus.
Represent!
When you draw a representation of an
atom, you must draw each particle in their
correct positions
For neutral atoms (atoms which have no
net charge), the number of protons must
equal the number of electrons.
Neutrality
When the number of protons equals the
number of electrons, then the number of
positive particles in the atom equals the
number of negative particles in the atom.
This results in the atom itself having no net
charge (being neutral).
Lithium - 7
Ex: Li (atomic # 3)
# of protons = 3
# of neutrons = 7- 3 = 4
# of electrons = 3
charge = (+3 – 3) = 0
Carbon - 12
Ex: C (atomic # 6)
# of protons = 6
# of neutrons = 12- 6 = 6
# of electrons = 6
charge = (+6 – 6) = 0
Neon - 20
Ex: Ne (atomic # 10)
# of protons = 10
# of neutrons = 20- 10 = 10
# of electrons = 10
charge = (+10 – 10) = 0