Atomic Radius

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Jedrick Zablan 3L
Posts: 68
Joined: Sat Aug 17, 2019 12:17 am

Atomic Radius

Postby Jedrick Zablan 3L » Sat Oct 26, 2019 2:11 pm

Why does atomic radius decrease from left to right and increase down the period. Thanks :)

Christine Honda 2I
Posts: 116
Joined: Sat Sep 14, 2019 12:17 am

Re: Atomic Radius

Postby Christine Honda 2I » Sat Oct 26, 2019 2:16 pm

Atomic size decreases from left to right across a period of elements. This is because protons are being added to the nucleus making it more positively charged as well as the fact that electrons are added to the same shell. This creates greater nuclear attraction and therefore the electrons are pulled in closer to the nucleus making the atom smaller.

Down a group, the atomic radius increases. The valence electrons occupy higher levels due to the increasing quantum number (n) and so the valence electrons are further away from the nucleus making the atomic radius bigger.

Annie Chantasirivisal_4G
Posts: 114
Joined: Wed Sep 18, 2019 12:21 am

Re: Atomic Radius

Postby Annie Chantasirivisal_4G » Sat Oct 26, 2019 2:25 pm

Atomic radii decrease from left to right because going across a period is essentially adding another electron in the same shell/energy level; the next element would also have an increase nucleus since protons and neutrons are also being added to cancel out charges. Thus, that increase in nuclear charge would attract the electrons much more (protons and electrons are attracted to each other due to opposing charges) and cause a pulling effect that makes the atomic radii become smaller across a period.

Atomic radii increase down a group because elements are changing by energy/shell level; the lower you are on the periodic table, the more electrons you will have, as suggested by the atomic number (gives us number of protons but consequently we'd know the number of electrons if the element was in ground state). Thus, when going down a period, the number of shells increases and the electrons are experiencing less of a pull from the nucleus since it is farther away and the electrons that are much closer to the nucleus would be shielding the outer electrons from the nuclear pull.

Jasmine Summers 4G
Posts: 50
Joined: Wed Sep 18, 2019 12:17 am

Re: Atomic Radius

Postby Jasmine Summers 4G » Sat Oct 26, 2019 3:09 pm

Atomic radius directly depends on how many electrons an element has because the more electrons an atom has, the larger it will be. Therefore it increases from left to right and from top to bottom along the periodic table.

Emma Joy Schaetz 1E
Posts: 43
Joined: Wed Sep 18, 2019 12:16 am

Re: Atomic Radius

Postby Emma Joy Schaetz 1E » Sat Oct 26, 2019 3:29 pm

The more electrons an element has, the larger it will be due to the increasing negative charge and the push of electrons apart as well as the addition of more orbitals i believe.

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