chemistry unit 1 Flashcards
electronic configuration (what are the letters for the sub levels, and what is the order for increasing energy)
the sub levels are assigned in letters. the letters are s,p,d and f.
each sub levels have different energy levels.
the order of increasing energy is 1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p, 52, 4d, 5p, 6s
how many electrons can each sub level hold.
s= 2
p=6
d= 10
f=14
why does the sub levels 4s fill first before 3d
this is because 4s is lower in energy but when atoms are ionised, electrons are removed from 4s before 3d.
explain 2p3
the number 2 shows that the electrons are on the second energy level. the P shows the sub level on which the electron is found. the 3 shows that there are three electrons on this sub level.
energy level diagrams and how many electrons can each box which represents an orbital contain
2 electrons
what is the electronic configuration for magnesium.
1s2, 2s2, 2p6, 3s2
electronic configuration of ions( what happens when an atom loses electrons and gains and what happens between 3d and 4s sub levels
when an atom loses electrons, they become a positive ion, when an atom gains electrons they become a negative ion.
the 4s fills before 3d because it is lower in energy but although the 3d sub level is higher in energy, electrons are removed from 4s before 3d
write the electronic configuration of mg2+
1s2 2s2 2p6
properties of ionic compounds
high melting and boiling points because they have strong electrostatic forces of attraction between ions so lots of energy is required to break the bonds, however this is dependent on size of the ion and charge of the ion.
the smaller the ion the stronger the bond, the higher the charge the stronger the ionic bond.
will only conduct electricity when molten or dissolves( in aqueous solution) because ions are free to move and carry charge.
they can dissolve in water because they from attractions with the different atoms in water so are pulled apart.
what is metallic bonding
strong electrostatic force of attraction between the positive metal ions and a sea of delocalised electrons
how many delocalized electrons are there
the number of delocalised electrons is proportional to the number of electrons lost by the atoms. for example, sodium will donate one electron per atom to the sea but magnesium will donate 2
properties of metallic bonding
giant metallic lattice, strength of metallic bonding depends on the number of electrons donated to the sea
good conductors of electricity
high mp and bp
malleable and ductile due to layers of ions that can slide over each other
melting point of group 1 metals
the mp decreases down the group. this is because larger metals have more electrons so more electron shells so more shielding between the nucleus and delocalised electrons( the inner electrons shield the outer electrons from the nucleus) this results in a weaker metallic bond so less energy needed to break the bonds
melting point of group 2 metals
same as group 1 metals they decrease down the group however the group 2 metals have a higher mp than the group 1 metals in the same period. this is because group 2 metals have two delocalized electrons per atom so have stronger electrostatic force of attraction between nucleus and delocalized electrons so a stronger metallic bond.
electronegativity
the ability/ power of an atom to attract a pair of electrons in a covalent bond. the power is given a numerical value and electronegativity is graded on a scale called the pauling scale
electronegativity trend
it increases across the table and as we move up the table
electronegativity example with hydrogen fluoride
fluorine is more electronegative than hydrogen so it will pull the shared pair of electrons closer to itself which produces a polar bond
what symbols are used for electronegativity
delta positive and delta negative which are partial charges
what do these charges represent
they represent less than a whole negative or positive charge. an atom that is more electronegative will be delta negative and pull electrons towards itself and away from the delta positive.
if atoms in the bond are the same what happens
the bond is non polar as they have an equal share of the electrons for example hydrogen, fluorine or chlorine.
explain what happens in london forces also known as van der waals forces
electrons are constantly moving randomly within shells of a molecule which causes an uneven distribution in the molecule at a certain point which causes an instantaneous temporary dipole. this dipole can induce a temporary dipole on another molecule which results in a weak attraction known as london forces.
the strength of the london force depends on the number of electrons a molecule has because the more electrons the more likely this process occurs
definition of intermolecular forces
interactions between molecules causes by permanent or induced dipoles
what are the features in order for a molecule to be symmetrical(non polar) and asymmetrical (polar)
for a molecule to be polar they would have to have pairs of electrons not used in bonding or a difference in electronegativity.
for a molecule to be non polar then they do not have any lone pairs and the electronegativity cancels out
are permanent dipole dipole interactions weak or strong
they are weak. the opposite ends of two molecules are attracted to each other which creates a weak force.
