Periodicity Flashcards
What is position of elements on periodic table linked to?
Chemical and physical properties
How is atomic number used in arrangement of the periodic table?
Increases from left to right across periodic table, each successive element has one extra proton
What is similar between each element in the same group?
Same number of outer shell electrons
Similar chemical properties
What does the number of the period indicate?
Number of highest energy electron shell in an element’s atom
Define periodicity
Repeating trend in properties of elements
What is ionisation energy a measure of ?
How easily an atom loses an electron to form positive ions
Define first ionisation energy
The amount of energy required to remove one electron from each atom in one mole of gaseous atoms of an element to form one mole of gaseous 1+ ions
What 3 factors affect ionisation energy?
Atomic Radius
Nuclear Charge
Electron Shielding
Do successive ionisation energies decrease or increase?
Increase because the electron is experiencing a greater attraction to the nucleus
What do large jumps in ionisation energy show?
Changes in shells
What are the 2 key patterns in ionisation energy in first 20 elements?
A general increase in first ionisation energy across a period
A sharp decrease in first ionisation between end of one period and start of the next
Explain trend in ionisation energy down a group
Decreases Atomic Radius increases More shells so shielding increases Proton number increases Nuclear attraction decreases Requires less energy to remove electron
Explain trend in ionisation energy across a period
Nuclear Charge increases
Similar shielding
Small atomic radius
First ionisation energy increases as more energy required due to greater attraction
Why is there a fall in ionisation energy between Be and B?
B has outer electrons in 2p which has higher energy level than the 2s sub shell and so is easier to remove because it is solitary and requires less energy, therefore first ionisation energy is less.
Why is there a fall between N and O?
O marks the start of pairing of electrons, the paired electrons in the 2p orbital cause repulsion which means that it is easier to remove an electron. Lowers first ionisation energy.
