Why does atomic size increase down a group but decrease across a period?

Moving from left to right across a period, electrons are added one at a time to the outer energy shell. Electrons within a shell cannot shield each other from the attraction to protons, while moving down a group in the periodic table, the number of electrons and filled electron shells increases.

Why does atomic size increase from top to bottom?

The atomic radius of atoms generally increases from top to bottom within a group. The effect of the greater number of principal energy levels outweighs the increase in nuclear charge and so atomic radius increases down a group. Figure 3. A graph of atomic radius plotted versus atomic number.

Why do both atomic size and ionic size increase as you move down a group?

Basically, as we move down the periodic table, the size of the nucleus increases, and concomitantly more electrons are present to “shield” the valence electrons from the charge. If there are many electrons, its harder to rope them up via electron charge than when there are less.

How does the atomic size vary on moving down a group?

Atomic size of an element increases down a group. This is because as one moves down a group its number of electrons increases(not arithmetically), so number of shells also increases. As a result of which atomic size increases.

Why does the atomic radius increase down Group 2?

Going down group 2: there are more filled shells between the nucleus and the outer electrons … so the electrons in the higher energy levels are further from the nucleus … the atomic radius increases.

How does atomic size change in period and group?

In general, the atomic radius decreases as we move from left to right in a period with an increase in the nuclear charge of the element. The atomic radius increases when we go down a group because of the addition of an extra shell.

What increases down group 2?

Progressing down group 2, the atomic radius increases due to the extra shell of electrons for each element. Going down the group, the first ionisation energy decreases.

What is the main reason for this decrease down the group?

Going down a group, the ionisation energy decreases. This is due to the shielding or screen effect of the outer electrons from the nucleus and so the attraction is weaker and they are more easily removed.

Why does atomic size decreases as we move from left to right along a period in a periodic table?

As we move from left to right across a period, the number of shells remain the same. As the atomic number increases, the nuclear charge increases and there is a greater attraction between the nucleus and the electrons. The atomic size, therefore, decreases across a period.

What is atomic size How does it vary in a group?

atomic size increases down a group since a new subshell is added. atomic size decreases across a period since an extra electron is added in same subshell increasing effective nuclear charge, and thus nucleus attracts subshell closer decreasing atomic size.

What decreases down group 2?

Ionisation energies decrease down the group. This is because each element down group 2 has an extra electron shell, so the outer shell electrons are further away from the nucleus which ultimately means a reduced nuclear attraction (the attraction between the positive nucleus and negative electrons).

Why does the atomic radius decrease as you move across the table?

Atomic radius decreases across a period because valence electrons are being added to the same energy level at the same time the nucleus is increasing in protons. The increase in nuclear charge attracts the electrons more strongly, pulling them closer to the nucleus.

Why does the radius of an atom increase down the group?

As one moves down the group there is significant jump in the size of the nucleus (Protons (atomic number) + Neutrons). The additions of new shells increases the distance between nucleus and valance electrons. this increases the pull effect of nucleus resulting in the increase in atomic radius of the atom.

Does atomic size increase down a group but decrease across period?

If you can remember Atomic size INCREASES down a Group, but DECREASES across a Period, where a Group is a column and Period is a row of the Periodic Table, you have mastered a fundamental principle of chemistry.

Why does effective nuclear charge increase down a group?

The effective nuclear charge, Zeff, increases down a group which draws electrons closer towards the nucleus, decreasing atomic radius. In respect to this, why does atomic radius increase in a group? This is caused by the increase in the number of protons and electrons across a period.

How does the number of electrons affect the size of atoms?

when we move down a group, the number of electrons increases. Each level (shell) only certain number of electron can occupy. If the number of electron further increased then, levels are increased. The electron start to occupy new space around the atom. So the atomic size increases.