bonding

Question 1

what is the most electronegative element

Answer 1

fluorine

Question 2

what is the definition of electronegativity

Answer 2

electronegativity is the power of an atom to attract the pair of electrons in a covalent bond

Question 3

what is a coordinate bond

Answer 3

a coordinate bond is a shared pair of electrons which come from the same atom
once formed coordinate bonds behave in the same way as any other covalent bonds

Question 4

what are the macromolecular structures

Answer 4

carbon
silicon
silicon oxide

Question 5

the bonding in mg is stronger than in sodium because

Answer 5

mg2+ has a greater charge than na+
mg2+ has more electrons(twice as many)
mg2+ is a smaller ion than na+
greater attraction between delocalised e- and the ions in mg than na

Question 6

strength of each IMF and how to figure out which IMF is present

Answer 6

1 H bonding
2 PDD
3 IDD
lone pair + H-N/O/F = h bonding
polar = PDD
non polar = IDD

Question 7

strength of repulsion

Answer 7

e- pairs repel as far as possible
lone pair-lone pair
lone pair-bonding pair
bonding pair-bonding pair
lone pairs repel more than bonding pairs

Question 8

properties of metals

Answer 8

conductivity-good conductors as delocalised electrons help transfer energy through the metal very effienctly.
strength of the metal-metals are strong as there is a strong electrostatic attraction between the positive metal ions and delocalised electrons
malleable and ductile-layers of metal ions slide past one another
high melting point and boiling point

Question 9

properties of ionic compounds

Answer 9

conduct when aqueous or molten
brittle-shatter easily
high melting point and boiling point - strong ionic bonds ionic lattice

Question 10

PDD

Answer 10

between polar molecules
weaker than Hydrogen bonding
arises: differnce in electronegativity leads to bond polarity
in non-symmetrical molecules dipoles do not cancel each other so molecules is polar and has overall dipole
partially +ve in one molecule is attracted to partially -ve in another
drawn image

Question 11

ionic compound formulae

Answer 11

charges in brackets
NH4(+)- ammonium
OH(-)-hydroxide
NO3(-)-nitrate
NO2(-)-nitrite
HCO3(-)-hydrogencarbonate
CLO(-)-Chlorate(I)
CLO3(-)-chlorate(V)
CO3(2-)-carbonate
SO4(2-)-sulfate
SO3(2-)-sulfite
Cr2O7(2-)-dichromate
PO4(3-)-phosphate

Question 12

importance of h bonding

Answer 12

ice- ice is less dense than water because of the h bonds . it holds ice molecules further apart
proteins- proteins are held in complex 3d shapes by h bonds
the N-H group of 1 amino acid h bonding to the C=O group on another amino acid
DNA- 2 strands are held by h bonds, strong enough to hold it together but weak enough to be separated for DNA replication

Question 13

IDD

Answer 13

weakest IMF - can be strongest if molecule is large
between molecules and atoms
arises: random movements of electrons
uneven distribution of electrons
temporary dipole in one molecule induces another dipole in another molecule
dipoles attract

Question 14

how to work out is a molecule is polar

Answer 14

look at atoms around central atom - if they are the same its symmetrical
lone paire = unsymmetrical
dipoles do not cancel each other

Question 15

H bonding

Answer 15

strongest IMF
between H - N/O/F and lone pair on N/O/F
arises: large difference in electronegativity between H and N/O/F
creates dipole in H-N/O/F bond
lone pair on O/N/F in molecule is attracted to H on another
drawn image

Question 16

graphite

Answer 16

soft-layers can slide over each other
weak intermolecular forces
attraction between layers
conductive-delocalised electrons are free to move carry current

Question 17

forces and properties of simple molecular structures

Answer 17

intermolecular forces act between molecules
when a simple molecular substances melts or boils it is the intermolecular forces that are broken
IMF-are much weaker than covalent bonds so simple molecular compounds have low melting point
strong covalent bonds between atoms in molecules

Question 18

factors that affect how electronegative an element is

Answer 18

shielding
nuclear charge
atomic radius

Question 19

diamond

Answer 19

high melting point-many strong covalent bonds
requires alot of energy to break
dont conduct electricity-no delocalised electrons to carry current

Question 20

describe a polar molecule

Answer 20

1 atom is more electronegative
electrons in a covalent bond are more closer to the more electronegative one

Question 21

describe a non polar molecule

Answer 21

atoms have same electronegativity
electrons shared evenly between atoms

Question 22

definition of metallic bonding

Answer 22

metallic bonding is the strong electrostatic attraction of positive ions surrounded by a sea of delocalised electrons.

Question 23

definition of ionic bonding

Answer 23

an ionic bond is the strong electrostatic attraction between oppositley charged ions
electrons are always transferred from the metal to the non metal

Question 24

definition of a covalent bond

Answer 24

a covalent bond is a shared pair of electrons between two atoms

Question 25

across period 2 the electronegativity increases because

Answer 25

shielding is the same
number of protons increase
ability of nucleus to attract electrons in a covalent bond increases