chemistry unit 1

Question 1

electronic configuration (what are the letters for the sub levels, and what is the order for increasing energy)

Answer 1

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

Question 2

how many electrons can each sub level hold.

Answer 2

s= 2
p=6
d= 10
f=14

Question 3

why does the sub levels 4s fill first before 3d

Answer 3

this is because 4s is lower in energy but when atoms are ionised, electrons are removed from 4s before 3d.

Question 4

explain 2p3

Answer 4

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.

Question 5

energy level diagrams and how many electrons can each box which represents an orbital contain

Answer 5

2 electrons

Question 6

what is the electronic configuration for magnesium.

Answer 6

1s2, 2s2, 2p6, 3s2

Question 7

electronic configuration of ions( what happens when an atom loses electrons and gains and what happens between 3d and 4s sub levels

Answer 7

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

Question 8

write the electronic configuration of mg2+

Answer 8

1s2 2s2 2p6

Question 9

properties of ionic compounds

Answer 9

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.

Question 10

how do the electrostatic forces act between the ions in the structures

Answer 10

act in all directions and keep the structure together

Question 11

what are positive ions known as

Answer 11

cations

Question 12

what are negative ions known as

Answer 12

anions

Question 13

what do ionic compounds have

Answer 13

giant structure that are arranged in a regular repeating pattern called a lattice.

Question 14

why does methane have a tetrahedral shape

Answer 14

this is becaus the orbitals containing lectron pairs repel as far away as possible which forms the shape

Question 15

what does it mean when bondlength and cond strenth are inversly related

Answer 15

this means that the shorter the bond length the greater the bond strength

Question 16

what is the bond angle around a carbon atom

Answer 16

109.5

Question 17

what is metallic bonding

Answer 17

strong electrostatic force of attraction between the nuclei of positive metal ions and a sea of delocalised electrons

Question 18

how many delocalized electrons are there

Answer 18

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

Question 19

how are delocalised elctrons formed

Answer 19

by the loss and free movement of the outershell electrons from the metal atoms

Question 20

properties of metallic bonding

Answer 20

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

Question 21

properties of metals

Answer 21

high mp and bp due to strong electrostatic attraction between positive ions and electrons, can conduct electricity due to electrons that are free to mov. malleable which means they can be shaped because layers of positive ions slide over each other and electrons mov with the layers same with ductility- can be pulled into wires becase ions roll over each other

Question 22

melting point of group 1 metals

Answer 22

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

Question 23

melting point of group 2 metals

Answer 23

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.

Question 24

electronegativity

Answer 24

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

Question 25

electronegativity trend

Answer 25

it increases across the table and as we move up the table

Question 26

electronegativity example with hydrogen fluoride

Answer 26

fluorine is more electronegative than hydrogen so it will pull the shared pair of electrons closer to itself which produces a polar bond

Question 27

what symbols are used for electronegativity

Answer 27

delta positive and delta negative which are partial charges

Question 28

what do these charges represent

Answer 28

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.

Question 29

if atoms in the bond are the same what happens

Answer 29

the bond is non polar as they have an equal share of the electrons for example hydrogen, fluorine or chlorine.

Question 30

explain what happens in london forces also known as van der waals forces

Answer 30

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

Question 31

how does size affect strength of the temp dipole

Answer 31

the bigger the molecule the more forces between molecules

Question 32

definition of intermolecular forces

Answer 32

interactions between molecules causes by permanent or induced dipoles

Question 33

how does a dipole occur

Answer 33

when there is an uneven distribution of electron density in the molecule

Question 34

what are the features in order for a molecule to be symmetrical(non polar) and asymmetrical (polar)

Answer 34

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

Question 35

are permanent dipole dipole interactions weak or strong

Answer 35

they are weak. the opposite ends of two molecules are attracted to each other which creates a weak force.

Question 36

do permanent dipole dipole interactions occur between polar molecules or non polar molecules

Answer 36

polar molecules because there is a difference in electronegativity between atoms so there is an attraction between delta positive on one molecule and delta negative on another molecule.

Question 37

explain a hydrogen bond, why it occurs and how to draw one

Answer 37

only occurs between polar molecules which have hydrogen directly bonded to oxygen nitrogen or fluorine. this is due to how electronegative o, n and f are so they will pull the electron towards themselves. show dipole charges on each atom, show lone pairs on o n and f and use a dashed line and if it was a water molecule, the oho bond should be 180 degrees.

Question 38

how to draw permanent dipole dipole diagram

Answer 38

same thing as hydrogen bond however do not draw lone pairs and draw a circle around each molecule with the circle being wider att the side that is more delta negative.

Question 39

what is relative molecular mass

Answer 39

the sum of the relative atomic masses of all the atoms present in the substances

Question 40

relative formula mass

Answer 40

sum of the relative atomic masses of all the atoms in the formula of the substance

Question 41

how to work out the mass of 1 mole of an element

Answer 41

its the same as its relative atomic mass in grams. for example, 24.3g of magnesium contains 1 mole of atoms.

Question 42

explain why electronegativity increases up a group

Answer 42

this is because the electron bonding pairs in the covalent bond will be closer to the nucleus attracting it

Question 43

why does electronegativity increase across a period

Answer 43

this is because nuclear charge increases so bonding between electron pair also increases but shielding stays the same