Why does atomic size increase as you go across a period?
Table of Contents
Why does atomic size increase as you go across a period?
Across a period, effective nuclear charge increases as electron shielding remains constant. A higher effective nuclear charge causes greater attractions to the electrons, pulling the electron cloud closer to the nucleus which results in a smaller atomic radius. This results in a larger atomic radius.
Why does atomic size increase from top to bottom?
(i) Atomic size increases as we move from top to bottom because each time one new shell is added and electrons in the outermost shell move away from the nucleus.
Why at the end of the period the atomic size of noble gases increases abruptly?
In a period, generally the size of the atom decreases with rise in atomic number, but at the end of each period, atomic size of the noble gas increases abruptly. In the case of noble gases, we measure Vander Waal’s radii instead of covalent radii since these elements do not form covalent bonds.
Why does the atomic radius decrease across Period 3?
Going across period 3: the number of protons in the nucleus increases so … therefore the force of attraction between the nucleus and the electrons increases … and the atomic radius decreases.
What makes atomic radius increase?
The gain of an electron adds more electrons to the outermost shell which increases the radius because there are now more electrons further away from the nucleus and there are more electrons to pull towards the nucleus so the pull becomes slightly weaker than of the neutral atom and causes an increase in atomic radius.
How does atomic size vary from left to right across a period and why?
Experiments have shown that the first case is what happens: the increase in nuclear charge overcomes the repulsion between the additional electrons in the valence level. Therefore, the size of atoms decreases as one moves across a period from left to right in the periodic table.
What happens to atomic size across a period class 10?
The nuclear charge is increasing and size of valence shell remains same as we move from left to right. Hence, in any period, the atomic size of the element decreases from left to right.
Why noble gases are inert?
When elements react, their atoms complete their outer shells by losing, gaining, or sharing electrons . The atoms of noble gases already have complete outer shells, so they have no tendency to lose, gain, or share electrons. This is why the noble gases are inert and do not take part in chemical reactions.
Why does atomic radius increase down a group but decrease across a period?
Across a period, the radius of elements decreases, since the effective nuclear charge gradually increases due to which electrons are attracted stronger towards the nucleus. However, down the group the atomic radius increases, as there is an increase in the number of shells within each atom.
What factors affect atomic size?
The actual trends that are observed with atomic size have to do with three factors. These factors are: the number of protons in the nucleus (called the nuclear charge). the number of energy levels holding electrons and the number of electrons in the outer energy level.
What factors affect atomic radius?
Explanation of the general trends
| factor | principle | effect on radius |
|---|---|---|
| nuclear charge | attractive force acting on electrons by protons in nucleus | decreases the atomic radius |
| shielding | repulsive force acting on outermost shell electrons by inner electrons | increases the atomic radius |
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