The periodic Table and the Elements...
All things are made up of element, which are arranged in the periodic table
Elements are made up of Atoms. An atom has a nucleus which contains protons and neutrons. (except hydrogen)
The nucleus is surrounded by orbiting electrons in the outer shells. These particles have different relative atomic masses and charges...
An atom has the saem number of protons as electrons, so the atom as a whole has no electrical charge. All the atoms in a particular element have...
- the same number of protons in their nuclei
- the same number of electrons orbiting the nucleus
Relative Atomic mass and atomic number...
The number at the bottom is the atomic number.- This tells us the number of protons (and electrons) found in the nucleus of an atom of that element.
The number at the top is the relative atomic mass.
Relative Atomic Mass
Atoms are to small for their actual atomic mass to be of much used to us.To make things more manageable we use relative atomic mass.
Relative atomic mass is the mass of a particular atom compared to 1/12 the mass of carbon.
The number of protons in the atom defines the element. All the atoms of a particular element all have the same number of protons in their nuclei; this number is unique to each particular element and is its atomic number...
However, some atoms of the same element can have different numbers of neutrons; these are called isotopes of the element. They have the same atomic number but a different mass number.
Relative atomic mass is an average for the different isotopes of an element.
...tells us how the electrons are arranged around the nucleus of an atom in energy levels (shells)
How an element reacts depends on...
- the number of electrons in the outermost shell
- the distance the outermost shell is from the nucleus
Group 1 : Alkali Metals
- become more reactive as we go down the group-this is becuase the outermost electron shell gets further away from the influence of the nucleus, meaning the electron is more easily lost.
Group 7: Halogens
-become less reactive as we go down the group- the outermost shells gets further away from the nucleus- meaning it is less attracted
Group 0/9-: Noble Gases
Do not react - they have full outer shells
...to become stable atoms lose/gain electrons in order to have 8 in their outer shell. These atoms must be accepted or donated by other atoms.
This results in ionic bonding
n ionic bond occurs between a metal atom and a non-metal atom and involves a transfer of electrons from one atom to the other in order to form electrically charged 'atoms' called ions. (+ or - charged)
Binary salt made form an anion and a cation
Ionic structures and Electrolysis...
Ionic compounds (sodium chloride etc) consist of a latice structure held by the forces of attraction between the positive ions (cations) and negative ions (anions)
Ionic compounds have..
- high melting/boiling points- strong forces
- conduct electricity when in molten or in solution
- oftern dissolve in water-forces of attraction formed in water
- are crysalline due to regular arrangement of their ions.
when a direct current is passed through a liquid containing ions, the ions move to the electrode with the opppiste charge.
The ions which are + move to the - cathode; the ions which are - move to the - anode
When the ions get to the electrodes they are discharged
Pure Metals and Alloys...
..A pure metal contains only atoms of that element. Most metals extracted from the ground need to purified...
- good conducts
- malleable (can be hammered without breaking)
- shiny- when polished
- high melting points and are ductile (can be drawn into wire)
- Sonorous (will ring when hit)
- Strong under tension and compression.
many metals are more useful when they are not pure.An alloy has a greater range of uses and is a mixture;
- lower melter point,
- increaesed corrosion, chemical, and strength resitance