Chemistry

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bob

Cards (27)

Dimitri Mendeleev 
Published the first periodic table in 1869.
He separated the elements into rows and columns according to their atomic mass and chemical properties.
What was impressive is that he left gaps for undiscovered elements.
The Periodic Law 
"When elements are arranged in order of increasing atomic, number there is a periodic repetition pf their chemical and physical properties"
This allowed Mendeleev to predict the properties of undiscovered elements.
Metals 
Mostly solid at room temperature.
Shiny (lustrous)
Conduct heat and electricity
Maluable
Ductile
Non-Metals 
Gas and liquid at room temperature.
Not lustrous or ductile
A small number are coloured
Have a larger range of melting and boiling points
Metaloids 
Have properties of both metals and non-metals. Most are un-metallic however some can be conductors
Alkali Metals- Group 1
Examples
Lithium (Li)
Sodium (Na)
One valence electron = is extremely reactive and forms ions with a +1 charge.
Reactivity increases as you move down the group. This is because the valance electrons are getting further from the nucleus and are easier to remove.
Melting and boiling points decrease as you move down the group.
Soft, silvery and shiny.
Light and float on water
React violently with water - often stored in oil
Alkaline earth metals - Group 2
Silverly metals
Less reactive then group 1 metals due to having 2 valance electrons.
Reactivity increases as you go down the group.
Form ions with + 2 charge.
Melting and boiling points are higher then group 1 metals but as you move down the table they decrease.
Eg:
Beryllium (Be)
Transition metals 3-12 
The most useful, colourful and valuable metals.
Most form colourful salts and solutions.
These are relatively hard and have high melting and boiling points. Some are magnetic.
They do not follow the octet rule. Electron shells are larger and closer together.
Halogens Group 17 
Quite reactive.
Have 7 valence electrons so only need one to fulfil the octet rule.
They have the electronegativity to easily gain this electron. Form ions with a -1 charge
Reactivity decreases as you move down because the electronegativity decreases as the outer shell moves further away.
As you go down, melting and boiling points increase.
Can form covalently (share one) or ionically (take one).
All convert hydrogen sulphide to sulphur (table salt)
All have coloured, poisonous vapors
Noble Gasses- Group 18
Non-metals
They are all colourless gasses that occur naturally in the atmosphere.
They all have a full outer shell which makes them unreactive.
As you go down the group the mass and density increase.
Helium and neon are lighter then air, argon,krypton and xenon are heavier then air.
Valence electron shell 
The outermost electron shell
Electron configuration 
1st shell = 2
2nd Shell = 8
3rd Shell = 8
Valence electrons 
The outermost electrons that are involved in bonding
Group and period from electron configuration
The number of valance electrons = group (skip 3-12 meaning 13 = 3)
Number of electrons = period
Ions 
Ions are charged particles formed by atoms losing or gaining electrons in order to get full shells.
Cations = positively charged
Anions = negatively charged
Neutral atoms
Have the same amount of protons and electrons.
All elements in a group have the same amount of valence electrons. 
Group 18: Full outer shells, do not make ions
Group 16 and 17: 6 or 7 valence electrons, gain electrons to get a full shell and become negatively charged anions
Group 1 and 2: 1 or 2 valance electrons
Aluminium: Group 13 metal, looses 3 outer valence electrons.
Ionic compounds 
Form when oppositely charged ions for an ionic compound.
Use the valency table to find charge and swap and drop
Ionic bond 
The electrostatic force of attraction between oppositely charged ions. Occurs between metals and non-metals.
Metals: Donate electrons and become cations
Non-Metals : Accept electrons and become anions
Structure of an ionic lattice
Ionic compounds for a lattice of interchanging positively and negatively charged ions. This is because ionic bonds work in all directions and can exist between many ions
Properties of ionic compounds
Non Malleable: Ionic substances are brittle because when a force is applied like charges align and repel each other.
Electrical conductivity: Ionic substances have charged particles due to their ions. In a solid state they cannot move, so they can't conduct electricity. In a liquid state they can move so they can conduct electricity.
High Melting/boiling point: strength of electrostatic attraction between ions is high.
Metallic Bond 
The electrostatic force of attraction between the positive metal ions and negative electron sea.
Metals exist as giant metallic structures made up of:
Lattice of positive metal ions
Delocalised electron sea
How are metallic bonds formed? 
Metals only have one, two or three valance electrons which they lose easily. When they lose the electrons they become positively charged and are attracted to the delocalised electron sea.
Properties of metallic substances
Malleable: When a force is applied and the particles move, there is still electrostatic attraction between the metal ions and the delocalised electron sea.
Electrical conductivity: Metallic substances can conduct electricity because they have a sea of delocalised electrons that are charged and can move
High Melting and Boiling points: because the electrostatic attraction between the metal ions and the sea of delocalised electrons is high.
Covalent Bonding 
Formed by the sharing of valance electrons to allow the formation of full outer shells of electrons.
This electron sharing generates an electrostatic force of attraction between the positive nuclei and the shared electrons.
Properties of covalent bonds
Malleable: weak attraction exists no matter where the particles are.
No electrical conductivity: don't have charged particles.
Low melting/boiling point: Low electrostatic attraction that is easy to beat.
Naming covalent compounds
Element found left is listed first
Last element is followed by ide
Prefix showing number