How did Mendeleev affect the Periodic table?
-In 1869 he organised the 60 known elements by atomic mass -He lined up elements with similar properties - He left space for elements which were yet to be discovered and predicted their properties
How is the Periodic table organised now?
-Elements are arranged according to atomic number
-In periods numbered 1 to 7 and by chemical properties in groups numbered 1 to 18
What are groups 3-12?
A trend that repeats across each period of the table
Define electron configuration?
The distribution of electrons of an atom or molecule in atomic or molecular orbitals
Define First Ionisation energy?
The energy required to remove 1 electron from each atom in 1 mole of gaseous atoms to make a mole of gaseous 1+ ions.
What three factors effect the first ionisation energy?
1. Atomic Radius
2. Nuclear charge
How does Atomic Radius effect 1st ionisation energy?
-The greater the atomic radius, the lower the nuclear attraction
-Less enery is required to remove the electron
- So the 1st Ionisation energy will be lower
How does Nuclear charge affect 1st ionisation energy?
-The more protons in the nucleus, the greater the nuclear charge
-Nuclear attraction increases
-More energy is required to remove the electron
-Ionisation energy will be higher
How does Shielding affect ionisation energy?
-Filled inner shells exert a shielding effect drecreasing the nuclear attraction
-Less energy is required to remove the electron
- So ionisation energy will be lower
Why is there an increasing trend in successive ionisation energies?
-Successive Ionisation energy increase in value
-Once an electron has been removed the remaining electrons experience greater nuclear attraction
-So more energy is required to remove the next electron.
What do 'jumps' in ionisation energy graphs show?
They represent a new shell so can be used to deduce group number and number of shells
Does atomic radius increase or decrease across period 3?
Why does the atomic radius decrease across period 3?
-Nuclear charge increases from Na to Ar
-Same shielding but more electrons
- so Nuclear attraction increases
-thus decreasing the atomic radius
Why does ionisation enery increase across the periods?
- Nuclear charge increases
-Same shielding as electrons enter the same energy level
-Nuclear attraction increases
-More energy required to remove the 1st electron
How is melting point patterned across the periodic table?
Increases from group 1-14
Decreases from group 15-18
Why is this pattern in melting point seen in the periodic table?
- Mpt is affected by bond strength/ structure
- Na to Si form Giant Lattices with strong bonds between atoms
- P to Cl form simple covalent molecular structures with weak intermolecular forces between molecules
- Ar is a monoatomic gas
- stronger bonds require more energy to break
What structure do Na,Mg and Al have?
Giant metallic lattice
What structure does Si have?
Giant covalent lattice
What structure does P, S, and Cl have?
Simple covalent molecular
What structure does Ar have?