Trends of the Periodic Table Flashcards
Identify 6 trends of the Periodic Table:
- Valency
- Atomic Radius
- Ionisation Energy
- Electronegativity
- Electron Affinity
- Metallic Character
Describe the trend of an element’s Valency in relation to the Periodic Table:
The number of Electron Shells increases (by 1 each row) as you move down the table, as more electrons are added and more shells needed to fit them.
The number of Valence Electrons an atom has increases (by 1 each group/column) as you move accross the table, to the right. This does NOT apply to the transition metals (groups 3-12).
In summary: The number of Valence electrons increases moving to the right, and the number of Valence shells increases moving down.
Describe the trend of an element’s Atomic Radius in relation to the Periodic Table:
Atomic Radius is the measured distance from the nucleus of an atom to its’ outer electron shell (Valence Shell).
As you move left along the groups, the number of protons in each atom decreases. Since electrons are attracted to protons, and there are less protons, there is less attractive force on the electrons, resulting in them not being ‘pulled in’ to the nucleus as much. Thus, an atom’s Atomic Radius increases as you move left accross the table.
As you move down through the periods (rows), the number of Electron Shells increases. Since there are more shells being added, the distance between the nucleus and the outermost shell is increased. Thus, an atom’s Atomic Radius increases as you move down the table.
In summary: Atomic Radius increases down and to the left.
Describe the trend of an element’s Ionisation Energy in relation to the Periodic Table:
Ionisation Energy describes how much energy would be needed to remove an electron from a neutral atom WHEN it is a gas.
As you move right along a period, the number of protons increases, so the positive charge of the nucleus also increases. The attraction between the nucleus and the electrons becomes stronger, which makes it harder to remove an electron, so more energy is needed. This means Ionisation Energy increases as we move across a period to the right.
As we move down a group, the electrons in their energy levels are getting further away from the nucleus, since more shells are being added. This means they are are less attracted to the nucleus, and it takes less energy to remove an electron. Thus, Ionisation Energy increases when we move up a group/column.
In summary: Ionisation Energy increases up and to the right.
Describe the trend of an element’s Electronegativity in relation to the Periodic Table:
Electronegativity is the ability of an atom to attract electrons towards itself.
As we move to the right along a period, the nucleus becomes more positive and the electrons are more closely attracted to it, resulting in a smaller atomic radius. The smaller atoms have a stronger attraction to electrons (since electrons can get closer to the positively charged nucleus) and are more electronegative. Thus, electronegativity increases as we move right across a period.
As as we move down a group, the number of energy levels increases, and the atomic radius increases. This makes it harder for an electron to be attracted to the atom as it cannot get as close to the nucleus. So, electronegativity increases as we move up the table, where the atomic radius is smaller.
In summary: Electronegativity increases up and to the right.
Describe the trend of an element’s Electron Affinity in relation to the Periodic Table:
Electron Affinity is the ability of an atom in a gaseous state to accept an electron and form a negative ion. Electron Affinity is different from electronegativity because it involves full addition of an electron, not just the ability to attract electrons.
As we move across a period to the right the atomic radius decreases. The outer shell becomes closer to the nucleus and its’ electrons more strongly attracted, so it becomes easier to add an electron.
As we move down the table, more electron shells are added, and the outer electron shell is further away from the nucleus, resulting in a weaker attractive force. This makes it harder to attract and add an electron to the atom.
In summary: Electron Affinity increases up and to the right.
Describe the trend of an element’s Metallic Character in relation to the Periodic Table:
Elements are classed as metals, non-metals or metalloids.
Elements on the left of the table are metals, while elements on the right of the table are non-metals. Metalloids are found in groups 13, 14, 15, 16 and 17, areanged in the pattern of a staircase.
In summary:
Metallic Character increases down and to the left.
- Metals are found on the left of the table
- Non-Metals are found on the right
- Metalloids exist on the right in a staircase pattern
Describe the trend of an element’s Reactivity in relation to the Periodic Table:
An elements’ reactivity increases as you move down the left side of the table, and up the right side.
