Trends in the periodic table Flashcards
(19 cards)
What are the 4 trends of the periodic table
- Atomic radius
2.Ionization energy
3.Electron affinity
4.Electronegativity
What is atomic radius
the estimated size of the atom from the nucleus to the outer shell
How does the atomic radius change over the periodic table
The radius gets bigger as you go down and to the left. Francium is big helium is small
What is the shielding effect
The more layers of electrons there are, the less the outer electrons feel attraction to the nucleus. The outer electrons are also repelled by the inner electrons
What happens to an atom as you go left to right on the periodic table? (period) why
in terms of atomic radius
The atomic radius decreases. While both protons and electrons are being added to the atom as we move right, the electrons are all on the same shell so it does not contribute to the shielding effect. This means the attractions force increases while the shielding effect stays mostly the same.
What happens to an atom as you go top to bottom on the periodic table? (group)
The atomic radius increases. A lot of electrons are added. Electrons in the inner energy levels block or shield the valence electrons from the attraction of the nucleus. Electrons are not held as tightly
What happens to a metal atom when it becomes an ion?
Metals lost electrons. There is less shielding effect. It gets smaller.
What happens to a non metal atom when it becomes an ion
Non metals gain electrons . More electrons make more shielding effect. The electrons are less attracted to the nucleus. The atomic radius increases.
What is ionization energy
The amount of energy required to remove an electron from a gaseous atom. The energy is measure in units of kJ/mol
What is first ionization energy
The amount of energy needed to remove the first electron from the atom. The least attracted electron in the atom
What are the trends of ionization energy along the periodic table
It increases as you go left to right on a period.
Decreases as you go down a group
What are factors of ionization energy(3)
Nuclear charge - num of protons, strength of pull from nucleus
atomic radius - Distance between the nucleus and the outer electron
Shielding effect - how much are the inner electrons shielding the outer ones
Trends of ionizatin energy
Increases left to right on a period
decreases down a group
opposite of atomic radius
what is electron affinity
The energy change that happens when you add an electron to a stable gas atom, forming an anion.
Energy is often released
kj/mol
Trend of electron affinity
increases from left to right and decreases down a group
The larger the amount of of energy released, the easier it is to add an electrons
due to increase in nuclear charge
What does a very negative number of electron affinity mean.
indicates that a lot of energy is released when an electron is added to a gaseous atom, and that such a process is very likely to occur.
what is electronegativity
The ability of an atom to attract the shared atoms in its bond
A high number means a high electronegativity and therefore a stronger attraction for electrons.
How is electronegativity measured
It is a relative scale.
categorized using physical properties such as ionization energy
The highest is 4.0 for fluorine.
What are the trends of electronegativity
and why
increases from left to right
- the number of protons increases but the shielding effect doesn’t. SO electrons are more attracted to the atom
Decreases down a group
- shield effect increases, electrons are less attracted to nucleus.
