1.Foundations in chemistry, Periodic table and enegy Flashcards
topic 1 and 2
Ionic bond definition
the electrostatic attraction between opp. charged ions
covalent bond definition
the strong electrostatic attraction between a SHARED PAIR of electrons and the NUCLEI of the bonded atoms
linear- bond angle /electron pairs/ example
180/ 2 bonding pairs of electrons / Co2
trigonal planar- bond angle /electron pairs/ example
120/ 3 bonding pairs of electrons/ Bcl3
tetrahedral- bond angle /electron pairs/ example
109.5 / 4 bonding pairs of electrons /CH4
pyramidal- bond angle /electron pairs/ example
107/ 3 bonding + 1 lone pair/ NH3
non-linear- bond angle /electron pairs/ example
104.5 / 2 bonding = 2 lone / H2O
octahedral- bond angle /electron pairs/ example
90 / 6 bonding pairs of electrons / SF6
electronegativity definition
the ability of an atom to attract the bonding electrons in a covalent bond
first ionisation energy definition
the energy required to remove one electron from every atom in one mole of GASEOUS ATOM
metallic bond definition
a strong electrostatic attraction between CATIONS and delocalised electrons
4 types of structure and boning
giant ionic
giant covalent
giant metallic
simple molecular/ covalent
describe the structure and bonding of a giant ionic lattice
-giant structure
-ionic bonding
-strong electrostatic forces of attraction
-in a GIANT IONIC LATTICE where forces act in ALL directions
3 properties of ionic compounds
-high melting/ boiling point
-conducts electricity when DISOLVED in water/ moltten
-poor conductors when SOLID
why do giant ionic compounds have a high melting point?
- strong elaectrostatic forces oif attraction IN ALL DIRECTIONS
-between opp. charged ions
-STRONG ionic bonds need lots of energy to break
why do giant ionic compounds have good electrical conductivity when molten/ dissolved in water?
-when molten/ disolved in water
-ions can m,ove freeley
-ions are mobile charge carriers
why do giant ionic compounds have bad electrical conductivity when solid?
-when solid
-ions are fixed
-and cant move
- are not mobile charge carriers
another word for dative covalent bonding?
coordinate bonding
why are electrons spread out in pairs?
-electron pairs repel ( as both are -ve)
-forced maximum distance apart
-lone pairs repel more than bonded pairs of electrons
(pairs of electrons repel other pairs of electrons)
pattern in electronegativity on the periodic table? and explination?
-increases as you move across a period (L-R)
more protons in the nucleus from (L-R)
increase in nuclear attraction between protons in the nucleus and electrons in the outer shells
-increases as you move up a grp
as you move up a grp atom size decreases
it is easier to get an electron closer to the nucleus
(increases in a diagonal across periodic table from FR to F)
what does a delta (δ) symbol show in a permenant dipole?
-a slight charge
δ+ is least electronegative
δ- is most electronegative
what is the most electrongative element?
flourine
what is a polar molecule?
- have bonds with a permanent dipole
-the molecular shape must not cause dipoles to cancel each-other out
what are the anomalous properties of water? and explain?
- Ice is less dense then water
coz ice has an OPEN lattice structure
Hydrogen bonds in the lattice hold the water molecuels
apart
-water has a relativley high boiling and melting point
coz it has hyfrogen bonds in addition to london forces
so more energy is needed to overcome the additional hydrogen bonds
what 3 elements can a hydrogen bond be formed with?
F
O
N
what delta charge is hydrogen
δ+
what delta charge does F/O/N have?
δ-
why metals have high melting point
-giant mettalic lattice
-strong metalic bonding
-lots of energy to break
why metals are good cobductors of electricity
have mobile delocalised electrons
which are mobile charge carriers
why metals dont disolve in water?
metalic bonds are too strong to be broken down by water
graphite structure
giant covalent lattice
layers of hexogons(trigonal planer angle 120)
each carbon atom has 3 strong covalent bonds
1 delocalised electron
graphite properties
good conducter of electricity
high melting point
desont disolve in water
why is graphite a good conductor of electricity?
each carbon atom has a delocalised electron
which can move through the structure
acting as mobile charge carriers
why graphit has a high melting point
giant covalent lattice
3 strong covalent bonds per atom
lots of energy to break
why dosent it disolve in wtaer?
not polar
has strong covalent bonds whicha re too strong to be broken down by water
structure of diamond and silicone
- giant covalent lattices
-each c atom has 4 strong covalent bonds
(no layers)
(no delocalised electrons)
diamond and silicone properties?
high melting point
why do diamond and silicone have a high melting point?
giant covalent lattice
4 strong covalent bonds per c atom
reuires lots of energy to break
why are silicone and graphite poor conductors of electricity
no delocalised electrons
which act as mobile charge carriers
nitric acid formula
HNO3
difference in melting point in the same period exsplained?
e.g P4 and cl2
P4 has a higher melting poit because it has stronger london forces (coz more e-)
more energy needed to break the intermolecular forces
why is a mollecule is polar
molecule isnt symetrical
dipoles dont cancel out
giant ionic lattice defenition
repeating pattern
of oppositley charged ions
orbital defenition
a region around the nucleus that can hold 2 el;ectrons (with opposite spin)
order of filling
1s/ 2s/2p/3s/3p/ (4s) /3d/4p
relative atomic mass (RAM) definition
weighted mean mass of an atom of an element to 1/12th of an atom of carbon- 12
relative isotopic mass (RIM)
the mass of an isotope relative to 1/12th of the mass of an atom of carbon-12
RAM equation
(mass x abundance) + (mass x abundance)/100
the 3 general reactions of acids
1) Acid + Alkali/base -> salt + water
2) Acid + Carbonate -> salt + carbon dioxide + water
3) acid + metal -> salt+ hydrogen
nutralisation reaction
H+ +OH- -> H2O
layers in an electron shell from biggest to smallest
shell-> subshell-> orbital
how many electrons in an orbital?
2
s subshell orbitals and electtrons?
s 1 orbital (2e-)
p subssell orbitals and electrons
3 orbitals n(6e-)
d subshell orbitals and electrons?
5 orbitals (10e-)
f orbitals
7 orbitals (14e-)
p orbital shape
dumbell
s orbital shape?
sphere
isotope definition
atoms with the same number of protons but a different number of nutrons and different masses.
what is the relative mass of an electron
1/1836
what are charges and masses of subatomic particles relative to
the proton