chemistry test revision Flashcards
covalent bonds
between non metal and non metal
ionic bonds
between metal and non metal
metallic bonds
between metal and metal
octet rule
valence shell can hold a maximum of 8 electrons
an atom is stable when…
it has a full valence shell
atomic radius
distance between the nucleus and valence electrons
why does atomic radius increase down a group?
- down the group, an extra shell is being added which increases the distance between the nucleus and valence shell
why does atomic radius decrease across a period?
across the period, the number of protons is increasing which makes the nucleus more positively charged, which attracts the electrons more strongly and shrinks the atoms size.
what occurs in ionic bonding
a non metal and metal donates electrons, they bond after sharing due to electrostatic attraction between the newly formed anion and cation
list properties of ionic bonds
high melting and boiling point due to strong bonds (more energy required to break)
not malleable or ductile - brittle due to strong lattice structure
explain why ionic compounds are hard but brittle
hard due to strong lattice structure with electrostatic forces. brittle because when force is applied, like charged ions line up, repel and therefore shatters.
do ionic compounds conduct electricity? why/why not?
NO. electricity is the movement of charged particles i.e electrons, the cations and anions are trapped in the lattice with no delocalised/ free moving electrons
why can metals easily conduct electricity?
as its electrons are delocalised, meaning they are free moving/ not fixed. this means they are able to carry charges and thus conduct electricity.
why are metals malleable
because the cations and electrons can maintain the electrostatic force of attraction when hit. ‘bent’ rather than shattered. the free moving electrons fill in the space to prevent like charges repelling
why are metals lustrous (extension)
they reflect light- light is in different wavelengths, and when it comes in contact to the electron, it gets absorbed for a second then vibrates, whihc reflects the light
two key ideas proposed by bohr model
- electrons exist in discrete energy levels called shells
- electrons can move between these discrete energy levels
strength of metallic bonding:
due to very strong electrostatic attractions, metals are very hard, as the metal cations are held together tightly in the metallic lattice. this leads to them being packed together tightly, making them dense.
why are group one and two metals more reactive going down a group?
because the valence shell is further from the nucleus which reduces the attraction between them, and the electrons are easier to lose as it is held onto less tightly.
describe valency in relation to covalent bonding
determines how many bonds an atom can form by sharing electrons to complete its outer shell.
describe the difference between covalent, ionic, metallic bonding
ionic- non metal and metals are DONATED/ ACCEPTED
covalent- non metal and non metals are SHARED
metallic- metal and metals’ valence e- are DELOCALISED
what happens to metallic character across the period (extension)
decreases, as the increasing effective nuclear charge makes it harder for atoms to lose e-
why do ions form?
to become more stable by gaining or losing electrons
atoms in group 13 likely have what charge?
+3
explain how atoms emit differnet colours of light
when electrons are excited, they jump from ground state to higher energy levels at excited state, as they fall different colours are emitted through different wavelengths.
