as you move left to right across period 3 from mg to cl, the energy needed to remove an electron from the atom does what?

increases. the left side of the chart is the easy to remove electrons.

To understand how the energy needed to remove an electron changes as you move from left to right across Period 3 of the periodic table, we need to consider the concept of electron affinity and the trend in atomic radius.

1. Atomic Radius: The atomic radius generally decreases as you move from left to right across a period. This is because the number of protons and electrons increases, creating stronger positive charge in the nucleus. The increased positive charge pulls the electrons closer to the nucleus, resulting in a smaller atomic radius.

2. Electron Affinity: Electron affinity is the energy change that occurs when an atom gains an electron to form a negative ion. It serves as an indication of how strongly an atom attracts an additional electron. In general, electron affinity tends to increase from left to right across a period.

Now, let's apply these concepts to the energy needed to remove an electron (ionization energy) as you move from left to right across Period 3 from Mg to Cl.

1. Magnesium (Mg) is located towards the left side of Period 3. It has a relatively large atomic radius since it is higher up in the periodic table and has fewer protons attracting the electrons. As a result, the energy required to remove an electron (ionization energy) is relatively low.

2. As you move across the period from left to right, the atomic radius decreases due to the increased nuclear charge. This means that the electrons are closer to the nucleus and more strongly attracted to it.

3. Chlorine (Cl) is located towards the right side of Period 3. It has a smaller atomic radius and higher nuclear charge compared to magnesium. Therefore, more energy is required to remove an electron from a chlorine atom since the electron is more strongly attracted to the nucleus.

In summary, the energy needed to remove an electron (ionization energy) generally increases as you move from left to right across Period 3, from Mg to Cl.