CHEMISTRY - Bonding, Structure and Properties Flashcards
what does malleable mean
can be shaped easily
what does ductile mean
can be pulled into a wire
what is a cation
particle with a positive charge, normally metals
what does lattice mean
a structure where particles are arranged in a regular pattern
what are delocalised electrons (aka free electrons)
electrons in a substance which don’t belong to a single bond
what is an anion
particle with a negative charge, usually non metals.
what is an allotrope
different structures of the same element
name 2 properties of ionic compounds and give an example
-conduct electricity only as a liquid or in a solution
-have medium to high melting points
NaCl - sodium chloride
what are 4 properties of metals and give an example
-conduct electricity as a solid only
-most have high melting points
-strong attraction between cation and free electrons
-ductile/malleable
gold
what are 2 properties of simple molecules (covalent) and give an example
-have very low melting points
-dont conduct electricity
oxygen
what are 2 examples of giant covalent substance and 2 properties for both examples
diamond
-very high melting point
-doesnt conduct electricity
graphite
-very high melting point
-conducts electricity as a solid only
why are metals good conductors of electricity
because their electrons are free to move (delocalised/free electrons) which carry a current
which two things help to bind a metallic bond as a single unit
and why
cations - positive charge
delocalised/free electrons - negative charge
in a metallic bond the positively charged cations and the negatively charged free electrons are attracted to each other and bind the metallic bond as a single unit
what creates a stronger metallic bond, and how many stronger metallic bonds be different to weaker metallic bonds
more free electrons in the lattice allows the metals to use it to make a stronger bond
stronger metallic bond’s properties and weaker metallic bond’s properties can be different
eg.
strong metallic bond = aluminium has a melting point of 1205 degrees and is a better conductor
but weaker metallic bond = sodium has a melting point of 98 degrees and is a worse conductor
describe how a diagram of a metalic bond would look like
cations would be arranged in neat rows ontop of each other
and there are free electrons around it all
one free electron per cation
what type of force holds cations together inside the lattice
an electrostatic attraction
what are ions
positively or negatively charged particles formed when atoms lose or gain electrons
how does a metal atom form into a cation (positvely charged )
metal atoms lose the electron or electrons in their outer shell and become positively charged ions
how does a non-metal atom form into an anion (negatively charged)
non metal atoms gain an electron or electrons from another atom to become negatively charged ions
how to find out the number of charged on an ion formed by a metal
look at the group number of the metal
eg. Na is in group 1, so its Na+
Mg is in group 2 so its Mg ²+
how to find out the number of charges on an ion formed by a non metal
8 minus the group number
eg. oxygen is in group 6 so, 8-6 = 2, so O²+
what happens when metals react with non metals
electrons are transferred from the metal atoms to the non metal atoms, forming ions. The resulting compound is called an ionic compound
to get all the marks, what four things must you ensure that you do when you are drawing and ionic bonding diagrams
-show outer electrons of every atom at the start (1 mark)
-an arrow showing the electron transfer of the electrons (1mark)
-square brackets around every ion formed (1 mark)
-correct positive or negative charge next to every ion (1mark)
list the 4 main properties of ionic solids
- high melting point (cuz of the strong ionic bond)
- high boiling point (because of the strong ionic bond)
- soluble (meaning it dissolves)
- conductor of electricity when its dissolved. (ions are moving, carrying current)
why do ionic compounds have such high melting points
strong electrostatic attraction (ionic bond) between the positive and negative ions
why do ionic compounds conduct electricity when dissolved/ as a liquid but not when its a solid
because as a solid, the ions aren’t moving and they are fixed, so they cant carry any current, but when dissolved/ as a liquid, the ions are free to move and can carry the electric current.
ionic bonds are forces of attraction between what?
between oppositely-charged ions
so positive and negative ions
what is it called when a metal and non metal react together
ionic bonding
what is it called when only non metals react together
simple covalent bonding
how do non metals do simple covalent bonding if they both need to gain electron(s)
they share it
eg.
hydrogen atom has noly one electron and needs one more to complete it’s first shell (since first shell capacity is 2 electrons, and all other shells are 8 capacity) and so when two hydrogen atoms get close together their shells can overlap and they share their electrons.
you can write this as H-H , with 1 line in between it to show it is a single covalent bond.
why do simple covalent bonds not conduct electricity
because the molecules are neutral - do not have any free electrons and carry no charge, so cant conduct electricity
why do simple covalent bonds have low melting and boiling points
due to weak intermolecular attractions. the covalent bond within the molecules are strong, but the forces between the molecules (intermolecular forces) are weak and little heat energy can overcome the force, leading to low boiling and melting points.
what are GIANT covalent bonds and give two main examples in GCSE chemistry
some covalent molecules are not simple compounds being formed from a few atoms,
they can be giant lattice structures with billions of atoms connected together - aka giant covalent bonds.
Diamond and Graphite (remember these two things, impotant)
what is an allotrope
different forms of the same element in the same physical state
describe what diamond is in terms of covalent bonds thingy
made up of a lattice of carbon atoms
each carbo atom can make 4 covalent bonds to 4 other carbon atoms
each out atom bonds to 3 more and so on
eventually millions of carbon atoms are bonded to form a giant lattice
describe what graphite is in terms of covalent bonds thingy
is made up of flat sheets of carbon atoms
each carbon atom makes 3 covalent bonds to other carbon atoms
this gives rings of 6 atoms
the flat sheets that lie on top of each other are held by weak forces - sometimes called van de waal’s forces.
what are the properties of diamond
- very hard- hardest known substance, each atom held to 4 others by strong covalent bonds - which is why it has a high melting point.
- doesn’t conduct electricity due to no ions or free electrons to carry charge.
what are the properties of graphite
- soft and slippery due to sheets of atoms being able to slide over one another because of weak forces between them
- a good conductor of electricity. this is due to each atom only using 3 out of 4 electrons in bonding. the fourth electron of each atom becomes delocalized (free to move) throughout the lattice, enabling graphite to carry charge.
- high melting point due to strong covalent bonds holding atoms of carbon together in the rings.
why does graphite conduct electricity?
3 out of the 4 electrons are used, and the 4th electron becomes free lectron, and carries electric curernt
give two uses of diamond and graphite and explain them
diamond
-drill tips - hard due to strong covalent bonds between atoms
-cutting tools - hard due to strong covalent bonds between atoms
graphite
-used as a lubricant - weak intermolecular forces between layers so they can slide
-used in electrodes - has a free electron that can move and carry charge
*electrodes are like conductors if ya didnt know
who discovered ‘bucky’ balls
sir harry kroto
what are bucky balls
spherical balls made from 60 carbon atoms. each carbon is attached to 3 others by strong covalent bonds. There is one free electron so they can conduct electricity
what are carbon nanotubes
another allotrope of carbon. they are molecular scale tubes of carbon atoms covalently bonded together with outstanding properties. each carbon is attached to 3 others by strong covalent bonds, with 1 free electron, so they can conduct electricity. they are flexible, strong and good conductors of electricity
what is nanotechnology
technology using very very small particles and substances. so small that it isnt possible to see them with the naked eye. “Nano” means 1 billionth”
name some properties of nano-particles of silver
-anti fungal
-anti bacterial
-anti virul
name 4 uses for nano silver
-deodrant
-socks
-clothes
-plasters
name two problems about nano silver
-long term effects aren’t known
-could be absorbed into your body and damage your health
are the properties of nano silver and normal silver the same
no, a nano particle of silver has different properties
name two other examples of nano particles other than silver and how they are used
nano particles of titanium oxide are added to sunscreen as it reflects UV radiation away
nano particles of gold can become red or orange or blue and can be stretchy. they can be used to connect conductors
what are smart materials
when you heat a material such as iron, it becomes malleable but it is pretty useless
smart materials are materials that can change due to change in temperature, pH, light or other stuff, and the change in the material will be useful, and the change can also be reverted.
name the 5 different types of smart materials
-thermochromic
-photochromic
-hydrogel
-shape memory polymer (polymer = plastic)
-shape memory alloy (alloy = metal)
both shape memory things are the same but theres 2 kinds, alloy and polymer
alloy is metal and polymer is plastic
what are the properties of thermochromic paint and the use of it
property
-colour changes at different temperatures - reversible
use
-“flat” thermometers battery testers, coating on coffee mugs.
what are the properties of photochromic paint and the use of it
property
-colour changes at different light intensity - reversible
use
-sunglasses, novelty items such as toys and cosmetics
what are the properties of shape memory alloy and the use of it
property
-it can be deformed and if you heat it up, it will return to the original shape
use
-coffee pot thermostat, spectacle frames, stents for veins
what are the properties of shape memory polymer and the use of it
property
-it can be deformed and if you heat it up, it will return to the original shape
use
-biodegradable surgical implants, self - repairing car bodies (easy dent removal)
what are the properties of hydrogels and the uses of it
property
-can absorb large volumes of water and also expel it
use
-artificial muscles, robot actuators, removal of toxic chemicals, nappies
what is the cause of the strength of a metallic bond?
the force of attraction between the positive charge metal ions and the negatively charged electrons.
what is a dot and cross diagram
diagram to represent ionic bonding or covalent bonding
