2.1-2.9 Flashcards
(34 cards)
define ionic bond
the electrostatic attraction between oppositely charged ions. mostly happens between metals and non-metals
what are the 6 main molecular ions?
hydroxide: OH^- nitrate NO3 ^- sulphate: SO4 ^2- Carbonate: CO3 ^2- hydrogen carbonate: HCO3 ^- Ammonium: NH4 ^+ Phosphate- PO4 ^3-
how to draw a dot and cross diagram for ionic compounds
the symbol goes in the centre,
draw the outer shell with dots and crosses
put in a bracket with the charge by the top right corner
and the ratio number next to the bottom right corner
define: coordination number
the number of oppositely charged ions surrounding one ion in an ionic lattice structure
explain the M.P of ionic compounds
they have strong electrostatic forces of attraction which require lots of energy to break.
explain the strength of ionic compounds
they are very brittle. any dislocation causes alike charges to be next to each other. these repel causing a fracture
explain the solubility of ionic compounds
only soluble in polar solvents. Solubility depends on the balance between the attraction of the oppositely charged ions to each other and the attraction of the separate ions to the solvent
explain the conductivity of ionic compounds
only conductive when aqueous of molten. the ions need to be free to move but they are stuck in place when solid
define covalent bond
the electrostatic force of attraction between the nucleus and the shared pair of electrons. only happens between non-metals
define hybridisation
when atoms move electrons to an unoccupied orbital in the same energy level to form more covalent bonds
what is a dative covalent bond?
when one atom donates both electrons in a covalent bond.
explain the m.p of simple molecules
it intermolecular forces are weak so very little energy is needed to separate the molecules
explain the conductivity of simple molecules
they don’t conduct electricity because there are no free ions or electrons
explain the solubility of simple molecules
depends on the polarity. tend not to be soluble in water
define electronegativity
a measure of the attraction between a bonded atom and the pair of electrons in the covalent bond
factors affecting electronegativity
nuclear charge- higher charge causes a stronger
attraction
atomic radius- closer to the nucleus causes a stronger
attraction
shielding- more shielding causes more repulsion so
the attraction is weaker
how does electronegativity change down a group and why
it decreases. the atomic radius and shielding increases. this causes a weaker attraction to the bonding electrons
how does electronegativity change across a period
it increases. the atomic radius decreases and the nuclear charge increases. this causes a stronger attraction to the bonding electrons.
whats a metallic bond
the electrostatic force of attraction between metal cations and a sea of delocalised electrons.
explain the density of metals
they have a higher density. this is because the cations are packed together tightly
explain the M.P of metals
it’s very high. the attraction between cations and sea of electrons is very strong so lots of energy is required
explain the solubility of metals
they are insoluble. the attraction between metal cations and electrons is much stronger than the attraction between water and metal cations
how does the M.P of metals change across a period
its increases due to the atomic radius decreasing and the number of delocalised electron per atom increasing. the strength of attraction between electrons and metal cations increases so more energy is needed.
how does the M.P of metals change down a group
it decreases due to the atomic radius and shielding increasing. this makes the attraction weaker so less energy is required.
