Assesment 2 Flashcards
(35 cards)
Formula for number of outer shells in grouped elements…
Group number = number of outer shells (excluding transition metals).
Suggest the charge for both fused elements in Beryllium Oxide…
X XX
X X
Be XX O XX
X X
X XX
\+2. -2
There is a ___________ between the ______ and _______ ions - this is an IONIC BOND.
There is a strong electrostatic attraction between the positive and negative ions - this is an ionic bond.
______ therefore happens between a ____ and _________.
Ionic bonding therefore happens between a metal and a non-metal.
The ____ make an _________ where each ion is surrounded by ions of the opposite charge - an __________.
This ions make an alternating structure where each ion is surrounded by ions of the opposite charge - an ionic lattice.
In reality, there are lots of ions all _______. The formula shows the ____ between the __. We call this ratio the ___________. The ionic compound overall is _____.
In reality, there are lots of ions all joined together. The formula shows a the ratio between the ions. We call this ratio the EMPIRICAL FORMULA. The ionic compound overall is neutral.
Electrostatic attraction-
Bringing electrons together.
List some of people the properties of materials:
Colour Density Structure Texture Malleable/brittle Sonorous Ductile Hard/soft Smell Shiny/dull Physical states of matter Melting points Boiling points Conductivity
Properties of ionic compounds
Hard brittle
High melting and boiling points (solid at room temp)
Conducts electricity when in solution
Easily breaks due to crystalline structure
Strong electrostatic Forces of attraction
Conducts electricity when molten dissolved as ions are free to move around - and carry charge
Does not conduct when solid
Covalent bonding List:
Sharing
Occur in non metals elements or compounds
Share electrons to get full outer shells
Each shared pair is a single covalent bond
Drawing covalent compounds
The outer shell should overlap and the shared pair of electrons should be inside the overlap bit.
Only draw the outer shell; this is the only one involved in bonding.
Use dots and crosses to show where the electron’s organised.
Chemical symbol for water
H2O
Chemical symbol for Ammonia
NH3
Chemical symbol for Methane
CH4
Chemical symbol for Carbon Dioxide
CO2
Simple covalent molecules
The covalent bonds between the atoms (within a molecule) are strong. There are only very very week intermolecular Forces between one molecule and the next.
This means that substances have ______________ - they are gases or liquids at _____________.
This means that substance have low melting and high boiling points - they are gases or liquids at room temperature.
The bigger the molecules the ______________, so melting and going points increase with _________.
The biggest the molecules, the stronger the forces, so melting and boiling points increase with size.
Simple covalent __________have no overall _________so cannot conduct electricity.
Simple covalent compounds have no overall charge so cannot electricity.
Properties of silicon dioxide
Large number of strong covalent bonds
High melting and boiling points.
Hard crystalline structure
No charged particles so cannot conduct electricity
Definition of polymers
Polymers are very large molecules made up of repeating units bonded together as long chains. They are represented by showing the original unit (monomer) and n to represent a large number eg poly(ethene)
Properties of poly…
The intermolecular Forces between polymer chains are relatively strong at the chains are so large.
This means they are solid at room temperature.
They are named after their monomer unit
Poly ethene
Poly propane
Polyvinylchloride (PVC)
Properties of diamond
Tetrahedral Hardest substance known to man High m and b points No conductivity Used in jewellery and cutting
Properties of graphite
Hexagonal Delocalised electrons Soft Night m and b points Conducts electricity Luberacant, pencils
