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Atomic Structure and the Periodic Table (The Periodic Table (Group 0 (The…
Atomic Structure and the Periodic Table
Atomis,Elements and Compounds
Atoms, Elements and Compounds
An
atom
is the smallest part of an
element
that can exist.
Elements
are displayed in the
periodic table
The atoms of each element are rapresented by a different
chemical symbol
: example- Sodium (Na), Chlorine (Cl)...
A
compound
contains atoms of
two or more elements
that are chemically bonded.
All substances are made of
atoms
Equations
You can sum up what has happened during a chemical reaction by writing a word equation or balanced symbol
equations
.
The
reactions
are on the the left-hand side of the equation.
The
products
are on the right-hand side of the equation.
Seperating mixtures
Mixtures
consist of two or more elements or compounds, which are not chemically bonded.
Mixtures
can be seperated by
physical processes
.
Filtration
is used to seperate soluble solids from: example- a mixture of salt (soluble) and sand (insoluble)
Crystallisation
Is used to obtain a soluble solid from a solution: example- salt crystals can e obtained from a solution of salty water
Distillation
is used to obtain a solvent from a solution
Chromatography
Is used to seperate a different soluble, colured components of a mixture: example- in a crime scene you can see with which colour ink the murdere used
Atoms and the Periodic Table
Subatomic particles
Atoms are very small and typically have an atomic radius about
Atoms contains
three types
of subatomic particles
Neutrons (=)
Protons (+)
Electrons (e-)
Almost all of the mass of an atom is in the nucleus
Isotopes and Ions
Def- Isotopes:
Of an element have the same number of protons but a different number od neutrons: example- Chlorine has two isotopes
Def- Ions:
Atoms can gain or lose electrones.
Metal atoms
lose of electrons to form
positive ions
. (As my teacher says that they are loosers)
Non-Metal atoms
gain electrons to form
negative ions
e.g: Sodium (Na):12 neutrons, 11 protones, 11 electrons (
looses -1 electron =10 electrons
) Fluorine (F):10 neutrons, 9 protons, 9 electrons (
gains +1 electron = 10
)
Electron Configuration
.
The
Electron configuration
of an atom shoes how the electrons are arranged around the
nucleus
in
shells
.
For the first
20 shells
-
The
first shell
can only hold maximum of
2 electrons
.
The next 2 shells
can each hold a maximum of
8 electrons
.
The Periodic Table
Did you know???
Dimitri Mendeleev
realised that some elements had yet to be discovered. When he created his table in 1869he left gaps to allow for their dicovery.
Group 0
The elements in
group 0
are known as the
noble gases
.
Noble gas atoms
have a full
outer shell
of
electrons
.
This means that these non-metas are
not reactive
, because they
don't
need more electrons from another atom
The boiling points of the
noble gases
increases down the group
Group 1
The elemnts in
Group 1
are known as
alkalai metals
All atoms from
Group 1
have
1 electron (e-)
in the outter shell
They have
low melting and boiling points
that decrease down the group.
More reactive down the group
This is because the
outer electron
gets further away from the influence of the
nucleus
(The gravity of the nucleus), so it could be lost easier.
Alkalai metals
are stored under oil because they react with
oxygen and water
, including moisture in the air: e.g- Na+H2O=NaOH+H2
Group 7
The
Group 7
elements are
non-metals
and are known as
halogens
.
Transition Metals
The
Transition Metals
are in the center of the periodic table (between groups
2
and
3
).
They can be used as
catalysts
to speed up
chemical reactions
.
