Bonding And Substances Flashcards
What is an ionic bond
A bond between a metal and non-metal involving the transfer of electrons.
What types of ions do elements in group 1 and 2 form?
Cations
Groups 1 metals will form 1+
Group 2 metals will form 2+
What type of ions do elements in the groups 6 and 7 form
Anions (negative)
Group 6 will form 2- ions
Group 7 will form 1- ions
What does it mean if an ionic compound ends in -ide
The compound contains 2 elements
What does it mean if an ionic compound ends in -ate?
The compound contains at least 3 elements, one of which is oxygen
Describe the structure of an ionic compound
Lattice structure
Regular arrangement of ions
Ions held together by strong electrostatic forced between ions with opposite charges.
What is a covalent bond?
A bond formed when an electron pair is sharer between two atoms.
What forms as a result of covalent bonding
A molecule
Draw a dot and cross diagram for formation of Methane (CH4)
Why do ionic compound have high melting points?
Strong electrostatic attraction between the positive and negative ions requires a lot of energy to overcome.
When do ionic compound conduct electricity? Why?
When molten or aqueous because ions are charged particles and are now free to move. When solid, ions can’t move.
Why do simple molecular compounds have low melting and boiling points?
They have weak intermolecular forces which only require a little energy to overcome.
Do simple molecular compounds conduct electricity?
No, there’s no charged particles.
Do giant covalent structures have a High melting point?
Yes, because they have lots of strong covalent bond which require a lot of energy break.
How do metals conduct electricity and heat?
The positive ions are fixed in a sea of delocalised electrons. These electrons are free to move and carry charge/energy.
Metals are insoluble in water. True or false?
True
Name two giant covalent structure formed from carbons atoms
Graphite
Diamond
Describe structure of graphite
Each carbon atom bonded to 3 other carbon atoms
Layers of hexagonal rings of carbon atoms
Weak intermolecular forces between layers
One delocalised electron per carbon atom
Describe and explained the properties of graphite
Graphite is soft/slippery because there are only weak intermolecular forces between layers which allow the layers to Slide Over one another.
Graphite conducts electricity because there is one delocalised electron per carbon atom. Delocalised electors are mobile charges.
Describe structure of diamond
All carbon atoms are covalently bonded to four other carbon atoms
No delocalised electrons
Describe the properties of diamond
Very hard
Very high melting point
Doesn’t conduct electricity as there are no charged particles
What are uses of graphite? Why?
Electrodes because graphite conducts electricity and has high melting point
Lubricant because it’s slippery (the layers in graphite can Slide Over each other)
Why is diamond used in cutting tools?
It’s very hard
What is a fullerene?
A molecule made of carbon, shaped like a closed tube or hollow ball.
Name two fullerenes
Graphene
C60 (Buckminsterfullerene)
What are properties of C60
Slippery due to weak intermolecular forces
Low melting point
Spherical
Strong covalent bonds between carbon atoms in a molecule
Large surface area
What are properties of graphene?
High melting point due to covalent bonding between carbon atoms
Conducts electricity because it has delocalised electrons
Why is graphene useful in electronics?
It is extremely strong and has delocalised electrons which are free to move and carry charge.
It is only one atom thick as it is single layer of graphite.
What is a polymer?
Long chain molecules formed form many monomers
Draw the structure of poly(ethene)
What bond is formed Between carbon atoms in polymer molecules
Covalent bonds
Properties of metals?
High melting point High density Good conductors of electricity Malleable and ductile Shiny
Why can metals conducts electricity?
The electrons in the metals are charges that can move.
Properties of non-metals
Low boiling points
Poor conductors
Brittle when solid
Limitations of: Dot and cross, 2D diagrams and 3D diagrams (in ionic compounds)
Dot and cross - no lattice structure or ionic bonds
2D - only shows one layer, doesn’t shown formation of ions
3D - doesn’t show charged, shows spaces between ions
Limitation of: dot & cross + ball & stick diagrams (in covalent molecules)
Dot and cross - doesn’t show the relative sizes of atoms or intermolecular forces
Ball and Stick - bonds shown as sticks rather than forces, doesn’t show how covalent bonds form.
Describe an experiment to work out empirical formula of magnesium oxide
Equation that links mass, moles and Mr together
Mass = moles x mr
What is avogadro constant?
The number of atoms, molecules or ions in one mole of a given substance
6.02 x 10^23
