Chapter 7 - Periodicity Flashcards
Who was responsible for a more accurate periodic table?
Mendeleev
What did Mendeleev do that was different?
He left gaps for undiscovered elements so that elements fir in patterns
What are the vertical columns in the periodic table called?
Groups
What are the horizontal rows in the periodic table called?
A period
How are the elements in the periodic table ordered?
By proton (atomic) number
4 Properties which vary across a period
Electron configuration
Ionisation energy
Structure
Melting point
How can the periodic table be used to work out electron configuration?
Each period signals the start of a new subshell, so you can read along the period and work out how many electrons are in each sub shell
What is the name for the elements in group 1?
Alkali metals
What is the name for elements in group 2?
Alkaline earth metals
What is the name for elements in groups 3-12?
Transition elements
What is the first ionisation energy of an element?
The energy needed to remove one mole of electrons from one mole of gaseous atoms
Why is ionisation an endothermic process?
It requires energy input
Equation for first ionisation energy
X (g) -> X+ +e-
What does a low ionisation energy indicate?
It is easier to form an ion
3 factors affecting ionisation energy
Nuclear charge
Atomic radius
Shielding
What does a high ionisation energy indicate?
There is strong attraction between the electron and the nucleus so more energy is needed to overcome it and remove the electron
How does nuclear charge impact ionisation energy?
The more protons there are, the stronger the attraction between the nucleus and electron will be
How does atomic radius impact ionisation energy?
The greater the distance between electron and nucleus, the weaker the force of attraction
How does shielding impact ionisation energy?
The more electrons shielding the electron from the nucleus, the weaker the force of attraction
Why does ionisation energy decrease down a group?
There is more electron shielding and the atomic radius is greater
Why does ionisation energy increase across a period?
There is a greater nuclear charge, so a stronger force of attraction