3.1.1 Periodicity Flashcards
what is periodicity?
repeating trends of physical or chemical properties
what are periods?
horizontal rows of elements
what are groups?
vertical rows of elements
where is the s block located on the periodic tables?
left
where is the p block located on the periodic tables?
right
where is the d block located on the periodic tables?
middle
what puts each element in the blocks?
outermost electron in each subshell
Atomic radius increases down a group (3 points)
> increase in no of shells
increase in shielding
outer electron is further from the nucleus
Atomic radius decreases down a group (3 points)
> no of protons increases
shielding is constant/ same
electrons are more strongly attracted to the nucleus and atomic radius decreases
what is the first ionisation energy?
the energy required to remove 1 mol of electrons from 1 mol of gaseous atoms
trend in the 1st ionisation energy down the group (5 points)
> ionisation energy decreases
increase in shells
more shielding
weaker attraction between nucleus and outer electron
less energy required to removed electron
Explain why first IE of Al(G3) is less that that of Mg (G2)? s to p block (3 points)
> IE decreases
electron is removed from a higher energy p subshell
weaker attraction between nucleus and outer electron
trend in the 1st ionisation energy across the periods (4 points)
across periods is an increase in IE
> IE increases
> no of protons increase
> shielding is constant
> stronger attraction between nucleus and outer electron
Explain why first IE of S(G6) is less that that of P(G5)? pair of sticks p3 to p4 (3 points)
> IE Decreases
there is a pair of electrons in p orbital
extra repulsion means less energy is required to remove the electron
Why is the first ionisation energy of beryllium greater than magnesium?(2 points)
> beryllium has less shells
stronger attraction between the outer electron and nucleus
Why is the first ionisation energy of strontium less than calcium?(3 points)
> strontium has more shells that calcium
weaker attraction between outer electron and nucleus
more shielding
Why is the first ionisation energy of magnesium greater than sodium? (3 points)
> Mg has more protons
same no of shells/ same shielding
stronger attraction between outer electron and nucleus
Why is the first ionisation energy of boron less than Be?(2 points)
> weaker attraction between the outer electron and nucleus
electron from boron is removed from the higher energy p subshell
Why is the first ionisation energy of oxygen less than nitrogen?(2 points)
> O- pair of electrons in p orbital
extra repulsion - less energy is needed to remove the electron
Why is the first ionisation energy of arsenic greater than selenium?(2 points)
> Se- pair of electrons in p orbital
extra repulsion - less energy is needed to remove the electron in Se
why does successive IEs always increase? (4 points)
> positive charge on the ion increases
ionic radius decreases
nuclear attraction on the outer electron increases
shielding is constant
what is metallic bonding?
strong electrostatic attraction between positive ions and delocalised electron
draw metallic bonding
what are the three main factors that affect the strength of metallic bonding?
- Number of protons/ Strength of nuclear attraction.
>The more protons the stronger the bond - Number of delocalised electrons per atom
>(the outer shell electrons are delocalised) The more delocalised electrons the stronger the bond - Size of ion.
>The smaller the ion, the stronger the bond.
Factors that affect Ionisation energy (3)
1.The attraction of the nucleus
> (The more protons in the nucleus the greater the attraction)
2. The distance of the electrons from the nucleus
> (The bigger the atom the further the outer electrons are from the nucleus and the weaker the attraction to the nucleus)
3. Shielding of the attraction of the nucleus
> (An electron in an outer shell is repelled by electrons in complete inner shells, weakening the attraction of the nucleus)
giant covalent structure
silicon
> bonding
> conduct electricity?
> bp/ mp?
> each silicon atom bonded to 4 other silicon atoms
strong covalent bonds require a lot of energy to break
no as there is no delocalised electrons
high the strong covalent bonds between atoms require a lot of energy to break
giant covalent structure
graphene (carbon)
> bonding
> conduct electricity?
> bp/ mp?
> each carbon atom bonded to 3 other carbon atoms forming a hexagonal layer
strong covalent bonds require a lot of energy to break
high the strong covalent bonds between atoms require a lot of energy to break
giant covalent structure
graphite (carbon)
> bonding
> conduct electricity?
> bp/ mp?
> each carbon atom bonded to 3 other carbon atoms forming a hexagonal layer
strong covalent bonds require a lot of energy to break
weak London forces between layers
high the strong covalent bonds between atoms require a lot of energy to break
giant covalent structure
diamond (carbon)
> bonding
> conduct electricity?
> bp/ mp?
> each carbon atom bonded to 4 other carbon atoms
strong covalent bonds require a lot of energy to break
no as there is no delocalised electrons
high the strong covalent bonds between atoms require a lot of energy to break
giant metallic lattice
> period 2 elements
> period 3 elements
> melting/ boiling points
> Li, Be
Na, Mg, Al
high mp and bp due to strong electrostatic attraction between positive ions and delocalised electrons
giant covalent
> period 2 elements
> period 3 elements
> melting/ boiling points
> C
Si
very high mp and bp due to strong covalent bonds which require a lot of energy to break
simple molecular
> period 2 elements
> period 3 elements
> melting/ boiling points
> N2, F2, O2, Ne
P4, Cl2, S8, Ar
low mp and bp as have weak London forces between molecules which require less energy to break
why is Ar and Ne monoatomic?
weak london forces between atoms
which ones got a higher first ionisation energy and why?
lithium or sodium
lithium
> less shielding
> less shells
> stronger attraction between nucleus and outer electron
which ones got a higher first ionisation energy and why?
aluminium or silicon
silicon
> same no of shells
> same shielding
> increase in protons
> stronger attraction between nucleus and outer electron
which ones got a higher first ionisation energy and why?
calcium or gallium
calcium
> gallium outer electron removed from high energy p sub shell
> gallium has a weaker attraction between nucleus and outer electron
describe and explain the trend in melting and boiling points of the period 3 metals
• increases
• charges increase
• size of ion decreases and no of electrons
• steonger metallic bonds increase due to stronger electrostatic forces of attraction between postitive ions and delocalised electrons
why does silicon have a very high melting and boiling point?
• strong covalent bonding between atoms require a lot of energy to break
• giant covalent structure
explain the trend in melting and boiling point of the simple molecular substances in period 3
• IDD forces increase with size of molecule and more electrons
• mp and bp decrease in order
S8>P4>Cl2>Ar
why does sodium have a higher melting point than ammonia?
• give the structure type
•name type of attraction being broken and relative strength
• compare melting points
• sodium oxide forms a giant ionic lattice, ammonia forms a simple molecular structure
• sodium oxide has strong electrostatic forces of attraction between oppositely charged ions
• the strongest intermolecular forces between ammonia molecules are hydrogen bonds
• ionic bonds are stronger than hydrogen bonds so required more energy to overcome the attractions
explain why the boiling points of fluorine and hydrogen fluoride are - 188°c and 19.5°c
• give the structure type
•name type of attraction being broken and relative strength
• compare melting points
• fluorine and hydrogen fluoride form a simple molecular structure
• the strongest IMD forces between hydrogen molecules are hydrogen bonds
• the strongest IMD forces between fluorine are PDD forces
• hydrogen bonds are stronger than PDD forces so requre more energy to break
metallic bonding is the strong … forces of attraction between positive metal ions and a sea of … electrons.
> electrostatic
delocalised
sodium, magnesium and aluminium all form … … … structures
giant metallic lattice
the boiling points increases from … to … because the … increases, the size … and the strength of the metallic bond increases.
> sodium
aluminium
charge
decreases
silicon is a …. ….. substance with strong … bonds extended throughout
giant covalent
covalent
phosphorus, sulfur, chlorine and argan form simple molecular structures, and have … forces between the molecules
london
sulfur exists as an S8 molecule so has the … amount of london forces between the molecules so has the … melting/boiling point.
highest
greatest
