Which trends are observed when the elements in Period 3 on the Periodic Table are considered in order of increasing atomic number?

(1) The atomic radius decreases, and the first ionization energy generally increases.

(2) The atomic radius decreases, and the first ionization energy generally decreases.

(3) The atomic radius increases, and the first ionization energy generally increases.

(4) The atomic radius increases, and the first ionization energy generally decreases.

i know its either 1 or 2 because i know the radius will decrease but i don't know about the ionization energy..

You are right. The radius decreases. But we can figures out the why for both parts by the following:

Think about this. Let's pick the first element in the period (Na) and the last element in the period (Cl).
Na has 11 protons (+ charge) in the nucleus. Cl has 17 + charges in the nucleus. Which will pull harder on trying to get those electrons (remember + charges attract negative charges) to come in with them. Of course, the 17+ charges will pull harder; therefore, the Cl is smaller than the Na.
Now for ionization potential.
If we are trying to pull the outside electron away, which will be harder? To pull an electron (with a negative charge) away from 11+ charges or to pull an electron away from 17+ charges. Of course it will be harder to pull an electron away from 17+ charges won't it. So the ionization potential generall increases as we go from left to right.

so that mean the answer is number 1?

yes

To determine the trends observed when the elements in Period 3 on the Periodic Table are considered in order of increasing atomic number, we need to analyze the properties of atomic radius and first ionization energy.

1. Atomic radius: The atomic radius refers to the size of the atom. As we move across a period from left to right (increasing atomic number), the atomic radius generally decreases. This is because the number of protons in the nucleus increases, resulting in a stronger positive charge that attracts the electrons more strongly. Consequently, the electrons are pulled closer to the nucleus, leading to a smaller atomic radius.

2. First ionization energy: The first ionization energy is the energy required to remove the outermost electron from an atom. As we move across a period from left to right, the first ionization energy generally increases. This is because the atomic radius is smaller, resulting in a stronger attraction between the positively charged nucleus and the negatively charged valence electron. Therefore, it becomes more difficult to remove the electron, requiring more energy.

Based on this information, we can conclude that option (1) is the correct answer: The atomic radius decreases, and the first ionization energy generally increases when the elements in Period 3 are considered in order of increasing atomic number.

What do you think and why?