atoms atoms are the building blocks of all matter. an atom is made up of smaller bits called…...
TRANSCRIPT
*Structure of the atom
ATOMSAtoms are the building blocks of all matter.
An atom is made up of smaller bits called…
Name Charge Position MassProtons
Electrons
Neutrons
+ve
-ve
neutral Nucleus
Outside
Nucleus 1
0
1
ELEMENTSAn element is a substance made up of only 1 type of atom. There are about 112 different atom types therefore there are 112 elements. These are shown on the periodic table of the elements.
On the periodic table each atom type has its information. For example…
Atomic no.
Symbol
NameAtomic mass.
PERIODIC TABLE
Any atom can be identified by the atomic no., the symbol or by the name. For instance...
Atomic no.
SymbolName
Name Symbol Atomic No.
Hydrogen
Fe
12
Iron
Magnesium
H
Mg
1
26
The information from the table can also be shown as:
11
5B
WHAT IT MEANSThe Atomic Number:
= number of protons
= number of electrons (as an atom has the same of each)
The Mass Number:
= number of protons + neutrons - why are electrons not included in the mass no?
They have no mass!
So for Boron…
Protons =
Electrons =
Neutrons =
5
5
6
What about Phosphorus?
Protons =
Electrons =
Neutrons =
15
15
16
11
5B
*Learning Check
Select the correct symbol for each:
A. Calcium
1) C 2) Ca 3) CA
B. Sulfur
1) S 2) Sl 3) Su
C. Iron
1) Ir 2) FE 3) Fe
*Learning Check
Select the correct name for each:
A. N
1)neon 2)nitrogen 3)nickel
B. P
1)potassium 2)phlogiston3)phosphorus
C. Ag
1) silver 2)agean 3)gold
ELECTRON ARRANGEMENT
Electrons are very fast moving. They are arranged in shells around the nucleus using the rule 2,8,8.
The first shell fits up to…
The second fits up to…
The third fits up to…
So the electron shell arrangement for 12Mg would be…
2 e
8 e
8 e
2, 8, 2
GROUPS
The columns in the periodic table are called groups. Groups of elements share similar reactivity.
This is because they have the same number of valence electrons.
As you go down a group the reactivity increases.
Group 1 are the alkali metals
properties: good conductors
solid at room temperatures
can be cut with a knife
low densities and melting points
Group 17 are the Halogens
*The rows in the periodic table are called periods.
*Atom’s size decreases from left to right in a given period
*The period tells you the number of energy shells in an atom.
*Periods
*Learning Check
A. Element in Group XVII, Period 4 1) Br 2) Cl 3) Mn
B. Element in Group II, Period 3
1) beryllium 2) magnesium 3) boron