AS - Unit 1 - The periodic table Flashcards
Give some advantages of Mendeleev’s table
Predicted the discovery of new elements
As a result their discovery did not disturb the organisation of the table
Indicated some accepted atomic weights were wrong
Give some disadvantages of Mendeleev’s table
Isotopes had not yet been discovered
Didn’t include any noble gases
What is a period?
A horizontal row of elements in the periodic table. Elements show trends in properties across a period
What is a repeating pattern of trends called?
Periodicity
What is each vertical column in the periodic table called?
A group
What does a group contain?
Elements with similar chemical properties
Atoms have the same number of outer shell electrons
What is periodicity?
A regular periodic variation of properties of elements with atomic number and position in the periodic table
What part of the atom is responsible for the chemical reaction?
The outer shell electrons
Why do elements in the same group react in very similar ways?
Each vertical group has the same number of electrons in its outer shell
And the same type of orbitals
Meaning they react in a similar way because they have similar electronic configurations
What factors affect ionisation energies?
Nuclear charge
Distance from the nucleus
Electron shielding
Why does ionisation increase across a period?
The number of protons increases, so the attraction between the nucleus and the outer electrons increases, so more energy is needed to remove an electron
this means the first ionisation energy increases across a period
Which was does a decrease in atomic radius occur?
Across a period, this is because the increased nuclear charge pulls the electrons in towards it
Starting the next period why is there a sharp decrease in first ionisation energy between the end of one period and the start of the next period?
It reflects the addition of a new shell, further from the nucleus which leads to:
increased distance of the outermost shell from the nucleus
increased electron shielding of the outermost electrons by the inner shells
What happens to first ionisation energies down a group?
It decreases because:
The number of shells increases
distance of the outer electrons from the nucleus increases
hence weaker forces of attraction on the outer electrons
there are more inner shells
so shielding effect on outer shells is greater
hence again, less attraction
There is a distinct change in boiling points between group 4 and 5, why is this?
the structure go from giant structures to simple molecular structures
from strong forces of attraction to wear forces of attraction
In metallic bonding, as ionic size increases, and thus attraction increases, what happens to the melting and boiling points?
They also increase
What physical properties do group 2 elements have?
Reasonably high melting and boiling points
light metals with low densities
form colourless compounds
Where are Group 2’s highest energy electrons?
In the S sub shell, along with group 1, they form the s-block of the Periodic table
What group in the periodic table contains strong reducing agents?
Group 2
What is the reactivity change in Group 2 of the periodic table?
It increases down the group, reflecting the increasing ease of losing electrons
What is the trend in ionisation energy in Group 2 of the periodic table?
Ionisation energy decreases down the group, due to the outer electrons being further away from the nucleus and therefore easier to remove from the atom
