C2/Bonding Flashcards
name 3 types of chemical bond
ionic bond
covalent bond
metallic bond
ionic bonds are formed between what type of particle?
by the attraction between oppositely charged ions
ionic bonds form between what type of elements?
they form between a metal and a non-metal element
how do covalent bonds form?
by the sharing of electrons
covalent bonds form between what type of elements?
they form between two non-metal elements
how do metallic bonds form?
by the sharing of delocalised electrons
metallic bonds form between what type of elements?
they form between two metal elements
in ionic bonding metal atoms gain electrons to become positively charged what?
ions
in ionic bonding non-metal atoms gain electrons to become ions with what charge?
a negative charge
group 1 metals commonly form ionic bonds with which group?
group 7
group 2 metals commonly form ionic bonds with which group?
group 6
ionic compounds form what type of structures?
giant ionic lattice structures
ionic compounds are held together by what?
strong electrostatic forces of attraction between oppositely charged ions
when atoms share pairs of electrons, they form what type of bonds?
covalent bonds
covalently bonded substances may consist of what size molecules?
small molecules
are covalent bonds strong or weak?
strong
some covalently bonded substances have very large molecules, such as what?
polymers
name 2 covalently bonded substances that have giant covalent structures
diamond
silicon dioxide
the electrons in the outer shell of metal atoms are delocalised and so are free to move to where?
throughout the whole structure
the sharing of delocalised electrons gives rise to what?
strong metallic bonds
name the three states of matter
solid, liquid and gas
both melting and freezing take place at what temperature?
the melting part of the substance
both boiling and condensing take place at what temperature?
the boling point of the substance
the amount of energy needed to change state from solid to liquid and from liquid to gas depends on what?
the strength of the forces between the particles of the substance
true or false?
the stronger the forces between the particles the lower the melting point and boiling point of the substance
false.
the stronger the forces between the particles the higher the melting point and boiling point of the substance
name 3 limitations with the simple particle model for solids, liquids and gases
no forces are shown
all particles are represented as spheres
the spheres are solid and inelastic
what state of matter is represented by (l)?
liquids
what state of matter is represented by (s)?
solids
what state of matter is represented by (g)?
gas
what state of matter is represented by (aq)?
aqueous solution
ionic compounds form regular structures (giant ionic lattices) which have what type of forces of attraction?
strong electrostatic forces of attraction in all directions between oppositely charged ions
why do compounds that form giant ionic lattices have high melting points and high boiling points?
because of large amounts of energy needed to break the many strong bonds
when melted or dissolved in water ionic compounds conduct electricity?
conduct electricity
why can melted or dissolved ionic compounds conduct electricity?
because the ions are free to move and so the charge can flow
substances that consist of small molecules are usually gases or liquids. do they have relatively low or high melting points and boiling points?
low melting and boiling points
gases have only weak forces between the molecules (intermolecular forces) is it the intermolecular forces or the covalent bonds that are overcome when the substance melts or boils?
intermolecular forces
true or false?
the intermolecular forces increase with the size of the molecules, so larger molecules have higher melting and boiling points
true
polymers are what type of molecule?
very large molecules
the atoms in the polymer molecules are linked to the other atoms by what type of bond?
strong covalent bonds
true or false?
the intermolecular forces between polymer molecules are relatively strong and so these substances are gases at room temperature?
false.
the intermolecular forces between polymer molecules are relatively strong and so these substances are solids at room temperature
substances that consist of giant covalent structures are solids with what type of melting point?
very high melting points
all of the atoms in giant covalent structures are linked to other atoms by what type of bond?
strong covalent bonds
why do metals have high melting and boiling points?
due to their strong metallic bonding
in pure metals, atoms are arranged in layers, what does this allow to happen?
it allows metals to be bent and shaped
pure metals are too soft for many uses and so are mixed with other metals to make harder what?
alloys
why are metals good conductors of electricity?
because the delocalised electrons in the metal carry electrical charge through the metal
why are metals good conductors of thermal energy?
because energy is transferred by the delocalised electrons
diamond is a giant covalent structure.
how many covalent bonds form between each carbon atom?
four
why is diamond very hard, with not a very high melting point and does not conduct electricity?
because the four covalent bonds between the carbon atoms
in graphite how many covalent bonds form between each carbon atom?
three
describe the layers in graphite
layers of hexagonal rings which have no covalent bonds between the layers
why does graphite conduct electricity?
because one electron from each carbon atom is delocalised and free to move throughtout the whole structure
what do we call a single layer of graphite that has properties that make it useful in electronics and composites?
graphene
what are fullerenes?
molecules of carbon atoms with hollow shapes
the structure of fullerenes is based on carbon atoms joined in what shape?
hexagonal rings
the first fullerene to be discovered was Buckminsterfullerene (C60) which has what shape?
spherical shape
what shape are carbon nanotubes?
cylindrical fullerenes with very high length to diameter ratios
what are fullerenes used for?
nanotechnology
electronics
materials
nanoscience refers to structures that are what size?
1-100 nm in size
what type of particles are smaller than fine particles (PM2.5) which have diamters between 100 and 2500 nm.
nanoparticles
what type of particles have diameters between 1 x 10-5m and 2.5 x 10-6m ?
coarse particles
coarse particles are often referred to as what?
dust
nanoparticles may have properties different from those for the same materials in bulk because of what?
their high surface area to volume ratio
the high surface area to volume ratio of nanoparticles means how much can be used?
smaller quantities than normal sized particles
nanoparticles have many applications.
name some of these.
in medicine in electronics in cosmetics in sun creams in deodorants in catalysts
the applications for nanoparticles an important area of what?
research
