Periodicity + Amounts of substance Flashcards
What force holds the protons and neutrons
strong nuclear force
what holds electrons and protons together in an atom
electrostatic forces of attraction
why is the nuclear force stronger than an electrostatic force
it overcomes repulsion between protons in nucleus
what decides the chemical properties of an element
the number and arrangement of electrons
why do isotopes have the same chemical properties
they have the same electron configuration
why do electrons fill orbitals singly before they start sharing
electrons repel eachother
name 2 transition metals with with unusual electron configurations
- copper Cu
- chromium Cr
they donate 1 of their 4s electrons to 3d sub-shell to make it full
what bonds form between group 4-7
covalent bonds to share electrons
why are the gases in group 0 enert
they have completely full s and p sub-shells
what type of process is ionisation
endothermic, you have to put energy in to ionise atom/molecule
name 3 factors that affect ionisation energy
- nuclear charge
- shielding
- distance from nucleus (atomic radius)
define ionic bonding
electrostatic forces of attraction between oppositely charged ions in an ionic lattice
chemical link between metal and non-metal
define covalent bonding
electrostatic forces of attraction between 2 nuclei and shared pair of electrons
between non-metals
define metalic bonding
electrostatic forces of attraction between delocalised electrons and positive ions in metallic lattice
which of Na+ and Mg2+ is the smaller ion and why
Mg2+
has more protons with the same amount of shielding
explain why ionisation energy decreases down a group
- atomic radius increases = electrons are further from nucleus
- more shielding = weaker nuclear attraction
explain why ionisation energy increases across a period
- number of protons increases = stronger nuclear attraction
- more electrons in the same amount of shielding
compare ionisation energy of group 2 and 3
- Aluminium’s outer electron = in 3p orbital rather than 3s
- 3p orbital = higher energy level than 3s orbital
- electron is found further from nucleus
- 3p orbital has more shielding provided by 3s2 electrons
- ionisation energy drops slightly, easier to remove electron
compare ionisation energy of group 5 and 6
(Shielding identical in phosphorus & sulfur atoms + electron is being removed from an identical orbital)
1. In phosphorus: electron being removed from singly-occupied orbital (3p3)
2. But in sulfur: electron removed from paired electrons in 3p orbital
3. Electron repulsion between 2 electrons = electron easier to remove from pair
how to write first ionisation energy
X(g) –> X+(g) + e-
define electronegativity
a measure of the tendency of an atom to attract a bonding pair of electrons
fluorine is most electronegative
what is avogadro’s constant
6.022 x 10^23
what is the conversion of 1 litre to dm3
1 l = 1 dm3
equation for concentration
n = c x v
unit for molarity
mol/l
mol/dm3
M
what are intra and inter molecular bonds
intramolecular bonds - act within a molecule
intermoleculer bonds - act between molecules
properties of ionic compounds
- high melting and boiling points
- water soluble
what type of bonds are single and double bonds
single bond = sigma bond
double bond = pi bond
properties of covalent bonds
- low melting and boiling points
define coordinate bond
covalent link between two atoms, but both of the shared electrons come from one of the bonding pairs
what are the 3 main types of intermolecular bonds in order of strength
- van del waals
- dipole-dipole
- hydrogen bonds
what are van der waals forces
an instantaneous slight negative charge when electrons briefly bunch together at one side of the atom
what are dipole-dipole forces
- when electrons in a polar molecule are pulled towards the more electronegative atom
- causing a slight negative charge at one end and a slight positive charge at the other end
what are hydorgen bonds
a weak electrostatic attraction between polar molecules which occurs when a hydrogen atom binds to a lone pair of electron on a highly electronegative atom
h-bonds between only NOF
