3.1- Periodic Table Flashcards
How many ways does the periodic table arrange elements in?
3
How are elements arranged in the periodic table?
- by increasing atomic number
- in periods
- in groups
What feature of atoms determines their reactivity?
The configuration of outer shell electrons
Which elements are in the S block?
Element from groups 1 and 2
Which elements are in the P block?
Elements in groups 3-7
Which elements are in the d block?
Element between groups 2 and 3
What is the definition of first ionisation energy?
The energy required to remove one mole of electrons from one mole of atoms in a gaseous state
What is the general trend of first ionisation energy down a group?
It decreases
Why does first ionisation energy decrease down a group?
- down the group, there is more shielding by the increase number of shells
- this also means the electron has a greater atomic radius and is further away
- this means there is a weekend traction between the nucleus and the electron, so it is easier to lose an electron
Why does the first ionisation energy increase across periods 2 and 3?
- across a period, there is an increase in nuclear charge so the atomic radius decreases
- there is no addition of new shells to shield outer electrons
- therefore, there is a strong attraction between the nucleus and outer shell electrons so they are much harder to remove
What is the general trend of first ionisation energy across periods 2 and 3?
It increases
Do all atoms follow these general trends?
No, there are smaller trends which link to orbitals
What can we use to work out the electron configuration of an unknown element?
Successive ionisation energies
Why is there a big leap in successive ionisation energies between neon and sodium?
- Sodium is a group 3 element with 8 electrons in its outer shell
- Removing an electron from this full outer shell requires lots of energy
What is the definition of second ionisation energy?
The amount of energy needed to remove one mole of electrons from mole of 1 + ions in a gaseous state
What is the symbol equation for first ionisation energy, Element M?
M—->M+ +e-
including gaseous state symbols
What three factors affect ionisation energy?
- Size of nuclear charge
- Amount of shielding
- atomic radius
List two examples in period 3 which do not appear to follow the trend of successive ionisation energy increasing across a period.
Magnesium to aluminium
Phosphorus to sulphur
Why does magnesium (group 2) have a greater ionisation energy than aluminium (group 3)? (not following the general trend)
- Aluminium has outer electron in the P orbital instead of the s orbital.
- A P orbital has higher energy so the electron is further from the nucleus
- This provides more shielding and even though there are more protons and hence a greater nuclear charge, the overall attraction is less so its easier to lose an electron
Why does phosphorus have a higher ionisation energy than sulphur? (not following the general trend)
- In Phosphorus, an electron is being removed from singularly occupied orbitals but in sulphur, an electron is being removed from an orbital containing 2 electrons
- The repulsion between 2 electrons means that electrons are easier to remove from the shared orbital, so sulphur has a lower ionisation energy than phosphorus
What is Periodicity?
Trends that occur in physical and chemical properties in the periodic table
What is electronegativity?
The ability of an atom to attract the pair of electrons within a covalent bond to itself
What is metallic bonding?
The strong attraction between the positive metal ions (cations) and the sea of delocalised electrons
How would you draw a diagram of metallic bonding?
- positive metal ions labelled
- free floating electrons( different number depending on if they are ions)
What is a giant covalent lattice?
What is an example of a giant covalent lattice?
A giant network of atoms all bonded covalently together
Diamond, graphite and graphine
What are the three forms of carbon?
Diamond
Graphite
Graphene
Why do metal lattices have a high melting and boiling point?
The atoms are closely packed together with strong attractive forces between ions and electrons
Lots of energy is required to move these fixed ions which means that has a high melting and boiling point
Why are metal lattices a good conductor of electricity?
They have delocalised electrons which are free to move and carry current, even in solid state
Why do giant covalent lattices have a high melting and boiling point?
They have very strong covalent bonds throughout the structure which need to be broken before melting or boiling can occur
Do giant covalent lattices conduct electricity?
It varies, if there are free electrons they can conduct there are no free electrons they can’t
Are giant covalent lattices soluble in water?
No, there are no ions to be solvated
Are metal lattices soluble in water?
No, they react with water instead