Topic 2: Bonding, structure and properties of matter Flashcards
how do metals form ions?
by gaining or losing electrons
what is an ion?
a charged particle
what makes an atom stable?
if it has a full outer shell
if two electrons are lost what will be the charge of the atom? (if it had a full outer shell)
2+
what groups on the periodic table mostly form ions?
1,2,6,7
what determines what group an atom is in on the periodic table?
the number of electrons in the outershell
what is an ionic bond?
A bond between a metal and a non metal caused by the attraction between the two due to the ion of one being positive and the other negative
in a dot and cross diagram what are dots representative of?
electrons in a non metal
in a dot and cross diagram what are crosses representative of?
electrons in a metal
how can you tell if a dot and cross diagram is of a ion or not?
because when it is an ion there will be brackets around it with the charge written in the top right
what ion would sodium form? 2,8,1
2,8 electrons
draw the ionic bonding of magnesium and oxygen?
2 magnesium atoms with brackets and negative charge and electron structure of 2,8,8
1 oxygen atom with brackets and a 2+ charge with electron structure 2,8
what is an ionic compound?
a giant structure of ions they are held together by strong electrostatic attraction between oppositely charged ions these forces act in all directions in the lattice
all ionic compound have similar propitiates, name some of these properties?
high melting point high boiling point (due to many strong bonds between the ions)
cant conduct electricity
how do you work out the empirical formula of an ionic compound?
work out how to balance out the charge (eg if one of them has a + charge and the other has a 2- charge you will need two of the positives to counteract the negative) once you have worked this out put the amount you would need of each atom next to its formula
what the empirical formula of potassium and oxygen ions?
potassium forms + ions and oxygen forms 2- ions so you will need two oxygen and one potassium making the empirical formula:
k 2 0
what is a covalent bond?
when two non metal atoms join together and share a pair of electrons
why are covalent bonds very strong?
because the positively charged nuclei of the bonded atom are attracted to the shared pair of electrons by electrostatic forces
where do covalent bonds happen?
compounds of non metals and non metallic elements
how do you draw covalent bonding?
you draw the atomic structure of the atom but you let the dots (in this case as they are non metals) overlap to show that they are sharing electrons. in this case you should draw one of the elements with a crosses the other with dots
what is the molecular formula of this: h h / / h-c-----c-h / / h h
c2h6 as there are 2 carbons and 6 hydrogens
what other than a dot and cross diagram can be used to represent covalent bonding?
lines for each covalent bond
what are simple molecular structures?
made up of molecules containing few atoms joined together by covalent bonds
give 6 examples of simple molecular structures?
- Hydrogen
- chlorine
- oxygen
- hydrogen
- methane
- water
- hydrogen chloride
what are the properties of simple molecular structures?
- low boiling point-
- low melting point
- most are a gas/liquid at room temperature
- don’t conduct electricity as they do not have an overall electric charge
what is a polymer?
very large molecules linked by strong covalent bonds with relatively strong inter molecular forces and so they are solids at room temperature
what is the structure of a polymer?
lots of small units formed together to make a long chain
what is the molecular formula of poly(ethene)?
(C2H4)n
what are polymers at room temperature?
solid
what is an allotrope?
different structural forms of the same element in the same state
what are fullerenes?
molecules of carbon atoms with a hollow shape the structure of fullerenes is based on hexagonal rings of carbon atoms but they may also contain rings with five or seven carbon atoms
why could fullerenes be used to transport drugs to the body?
because it can be used as a ‘cage’ due to the structure being circular or cube shaped
what is metallic bonding?
when there is a strong electrostatic attraction between the positive ions and the negative electrons which is what holds them together