Answer:

Explanation:
Atomic radius is the measurement from the nucleus to the outer edge of the electron cloud.
As you go down a group (vertically) the atomic radius increases because more electron shells are added. As you go across a period horizontally, the atomic radius decreases.
If we look at the halogens group (17), we see they follow this order from top to bottom:
F - Fluorine
Cl - Chlorine
Br - Bromine
I - Iodine
Since it increases down the group, iodine must have the largest atomic radius.
The study of the elements and forms of matter.
6.022*10^23 is the number
Explanation:
Speed and velocity are both used to describe the motion of a body. But there are differences between the two terms.
- Velocity is the rate of change of displacement with time. It is mathematically expressed below:
Velocity = 
The unit of velocity is m/s or km/hr.
Velocity is a vector quantity that shows magnitude and direction.
- Speed is the rate of change of distance with time. It is concerned with the total length of path a body moves.
Speed = 
It has the same unit as velocity
It is a scalar quantity that has only magnitude.
learn more:
Velocity brainly.com/question/10883914
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There are 18 protons in one atom of ³⁷Ar.
The number 37 is its <em>mass number</em> — the number of <em>protons + neutrons</em>.