Periodic Trends Flashcards
(22 cards)
What doesn’t have a definite edge?
An electron cloud.
What happens to the atomic radius in a group?
As we go down the group, the atomic radius increases.
Why does the atomic radius increase down a group?
Because there are more protons and neutrons, which makes the nucleus larger and there are more energy levels required for the electrons.
What happens to the atomic radius in a period?
The atomic radius decreases as we go from left to right because there is more pull on the electrons from the nucleus which causes the atom to be sucked inwards.
What are isoelectric ions?
Ions that have an equal number of electrons are isoelectric.
How are cations formed?
Cations are formed by losing electrons and becoming positive.
Are cations smaller than the atom they came from? (true/false)
True.
Which elements form cations?
Metals.
How are anions formed?
Anions are formed by gaining electrons and becoming negative.
Are anions bigger than the atom they came from (true/false)?
True.
Which elements form anions?
Metals.
What is electronegativity?
It is the tendency for an atom to attract a bounded electron to itself when it is chemically combined with another element.
What happens it the electronegativity as you go down a group?
The E.N decreases down a group as the atom is larger thus less pull and the atom is more likely to give away the valence electrons.
What happens to the electronegativity as you go from left to right across a period?
The E.N increases as the atom is smaller and there is more pull between the nucleus and electrons.
What is the shielding effect?
It is the effect that causes the electrons in the lower energy to shield the positive charge of the nucleus causing the outer electrons to be loosely held.
What is effective nuclear charge?
It is the average nuclear charge felt by an individual electron in an atom, taking into consideration the “shielding” effect of the inner shell electrons.
What is ionisation energy?
It is the energy required to remove an electron from atom in a gaseous state.
What is the formula used to represent ionisation energy?
A(g) —-> A+(g) + e-
What does ionisation always result in?
It always results in both the ions having 8 valence electrons.
What charge do ionisation energies have to be and why?
They always have to be positive because energy is supplied to remove an electron.
What does ionisation energy measure?
It measures how tightly the outer shell electrons are held in the atom.
What is the formula for effective nuclear charge?
Zeff = Z - S
