Question

Sodium is in Period 3, Family 1 (the Alkali Metals Family) The trend described across the period is Atomic Radius. The radius of an atom decreases from left to right across a period since the electrons are held _________ by the_________ number of ________ .

1. More closely,increasing, protons
2. Tightly , growing,nucleons
3. Attracted, rising ,electrons

Answer 1

The atomic radius decreases across a period due to the increasing number of protons, which strengthens the nucleus-electron attraction and pulls electrons closer, reducing the size of the atom.

Step-by-step explanation:

The atomic radius of atoms generally decreases from left to right across a period. This is because as you move across a period, the number of protons in the nucleus (Z) increases. This results in a stronger electrostatic attraction between the positively charged nucleus and the negatively charged electrons.

The electrons are held more closely by the increasing number of protons, leading to a reduction in the size of the atom. The correct sentence to complete the statement would be: The radius of an atom decreases from left to right across a period since the electrons are held more closely by the increasing number of protons.

Answer 2

The atomic radius decreases from left to right across a period due to the increasing number of protons, which cause electrons to be held more closely, fulfilling option 1: 'More closely, increasing, protons'.

Step-by-step explanation:

The atomic radius decreases from left to right across a period on the periodic table. This is because the number of protons in the nucleus increases, causing a stronger nuclear charge that pulls electrons closer to the nucleus. As a result, the electrons are held more closely by the increasing number of protons.

The correct completion of the sentence provided by the student would be option 1: 'More closely, increasing, protons'. This reflects the periodic trend that the attraction force between the positively charged nucleus and the negatively charged electrons becomes stronger as more protons are added to the nucleus, resulting in a smaller atomic radius.

The trend across the period for atomic radius can also be affected by electron-electron repulsion, which is why sometimes there are exceptions to the general trend, such as the slight increase in radius from nitrogen to oxygen.