structure and bonding test 2 Flashcards
what r 3 types of bonding
ionic,covalent,metallic
what is ionic bonding between
metals and non metals
what is covalent bonding between
non metals
what is metallic bonding been
metals
define ionic bonding
a strong electrostatic force of attraction between oppositely charged ions
what diagram do u draw for ionic bonding
dot and cross diagram
in general the larger the charge the what…
the larger the charge the stronger the attraction and the stronger the bond
whats the ionic structure
giant ionic lattice
properties of ionic structure and why
high melting+boiling point - a lot of energy is needed to break the strong electrostatic force of attraction between oppositely charged ions
electrical conductivity (non conductor as a solid) - the ions are held in fixed positions so cannot move and carry a charge. solutions and molten ionic substances are conductors - the ionic lattice breaks down so the ions are free to move and carry a charge
most ionic substances are soluble in water
what is covalent bonding and what diagram do u use
covalent bonding is the sharing of pairs of outer shell electrons between non-metal atoms
dot and cross diagrams
what do most covalent substances exist as
covalent substances exist as simple covalent molecules no covalent bonds are broken when ,melting or boiling molecules
properties of covalent bonds
low melting + boiling point - not a lot of energy is needed to overcome the weak intermolecular forces between simple covalent molecules
the larger the molecule the stronger the intermolecular forces the higher the melting and boiling points
non-conductors of electricity - there is no overall charge on molecules and there r no charged particles that can move
what structures do most covalent bonds have
giant covalent structures
give 3 things that have giant covalent structure
diamond, graphite, silica (silicon dioxide)
structure of diamond and give properties
each carbon atom is bonded via 4 strong covalent bonds to 4 other carbon atoms
very hard - strong covalent bonds to each carbon
very high melting point - a lot of energy is needed to break the strong covalent bond
non - conductor - No overall charge/no charge particles free to move
structure of graphite and give properties
each carbon forms 3 strong covalent bonds with a delocalised electron from each carbon between the layers. it has layers of hexagonal rings of carbon with weak forces between the layers
conductor - delocalised electrons free to move between layers
soft - layers can slide due to weak forces
high melting point - a lot of energy is needed to break the many strong covalent bonds
allotrope definition
different forms of the same element which exist at the same temperature and pressure
carbon allotropes example
graphite, diamond, graphene, fullerenes, carbon nanotubes
what is graphene
graphene is a single sheet of graphite
what are fullerenes
fullerenes are simple molecules used in lubricants and electronics
structure of fullerenes
hollow, spherical, hexagonal/pentagonal rings of carbon
what was the first fullerene to be discovered
the first fullerene to be discovered was Buckminster fullerene (60 carbon nanotubes)
what are carbon nanotubes
carbon nanotubes are cylindrical fullerenes with a high length to diameter ratio
what type of structure is Buckminster Fullerene
simple molecule
properties of metals
electrical conductor - delocalised electrons r free to move and carry charge
high melting point - A lot of energy is needed to overcome the strong electrostatic force of attraction between positive metal ions and a sea of delocalised electrons
ductile/malleable/soft - positive metal ions are arranged in neat rows that can slide past each other whilst remaining bonded
heat/thermal conductors - energy is transferred by the delocalised electrons moving through the structure
high density (especially transition metals) - they have a tightly packed lattice structure ( large mass to volume ratio)
dust is a what particle and has a size of?
dust is a coarse particle (PM10) which has a size of 10,000-25000nm
what do fine particles have a size of
fine particles (PM2.5) have a size of 100-2500nm
what size are nanoparticles
nanoparticles are the size of a few hundred atoms equivalent to 1-100nm, 1nm=1x10-9m
are nanoparticles or atoms larger
nanoparticles r larger than atoms because they’re made up of a few hundred atoms
as a material is divided into smaller and smaller particles what increases
As a material is divided into smaller and smaller particles, the overall surface area increases
as the side of a cube decreases by a factor of 10, what does the surface area to volume ratio increase by
as the sides of a cube decrease by a factor of 10, the surface area to volume ratio increases by a factor of 10
nano particles have a very high or low surface area to volume ratio compared to the same material in bulk this gives them very different properties
nano particles have a very high surface area to volume ratio compared to the same material in bulk this gives them very different properties
uses of nano particles
medicines,electronics,catalysts,cosmetics(e.g. sunscreen)
risks of nanoparticles
explosions, absorption through skin and in blood, lung damage
why is chlorine gas at room temp
The intermolecular force of chlorine is weak, and the heat required to break the force is less than iodine and bromine at room temperature.
why is sulfur dioxide harmful to the environment
When sulfur dioxide combines with water and air, it forms sulfuric acid, which is the main component of acid rain. Acid rain can: cause deforestation. acidify waterways to the detriment of aquatic life.
why is diamond hard
The rigid network of carbon atoms, held together by strong covalent bonds, makes diamond very hard
why can graphite be used in pencils
Graphite molecules are flat groups of carbon atoms that are stacked in layers. The layers slide against each other and allow the lead to slide off the pencil point and onto the paper
why are alloys harder than pure metals
They are made up of atoms of different sizes, rather than being uniform. This means that the layers of atoms cannot slide over each other easily, making the whole alloy much stronger than any of the pure metals
