Which of the answer choices accurately describes a trend that occurs when moving left to right across periods?
Select all that apply.
1 atomic mass increases
2 atomic radius increases
3 reactivity increases
4 valence electrons decrease
2 and 3?
2 is ok.
Think about 3. Does Mg have more reactivity than Na. Does Ca have more reactivity than K?
Think about 1. Except for a few hitches, doesn't atomic mass increase?
To determine the trend that occurs when moving left to right across periods on the periodic table, we need to understand how the properties of elements change.
1. Atomic mass: The atomic mass generally increases when moving left to right across periods as the number of protons and neutrons in the nucleus increases.
2. Atomic radius: The atomic radius generally decreases when moving left to right across periods. This is because, as you move across a period, the number of protons in the nucleus increases, leading to a stronger electromagnetic pull on the electrons, causing them to be pulled closer to the nucleus.
3. Reactivity: Reactivity can vary across periods and depends on various factors, such as the number of valence electrons and the electronegativity of the element. It is not a consistent trend, so it cannot be accurately described as always increasing or decreasing.
4. Valence electrons: Valence electrons generally increase when moving left to right across periods. This is because, as you move across a period, the number of electrons increases, and the outermost electron shell becomes closer to being filled with electrons.
Based on the explanations above, the correct answers are:
- Atomic radius increases (incorrect)
- Reactivity increases (incorrect)
- Valence electrons decrease (incorrect)
None of the answer choices accurately describe the trend when moving left to right across periods.