Question

1. a student uses the periodic table to predict properties of an element in period 5. the student makes these predictions: 1. q will have 7 valence electrons. 2. q will form q - ions. 3. q will be a non - metal. 4. q will be a solid at room temperature. which predictions are most likely correct based on periodic trends? predictions 1 and 2 only because they are common in group 17. predictions 1, 2 and 3 only because they follow group trends. all four predictions, because they all follow established periodic trends. predictions 1, 2 and 4 only because group 17 elements follow these patterns.

Explanation:

Step1: Analyze element in Period 5 with 7 valence electrons

Elements in period 5 with 7 valence electrons are halogens in that period. Halogens have 7 valence electrons and tend to gain 1 electron to form anions with a - 1 charge, so they form $X^-$ ions.

Step2: Determine the nature of the element

Halogens are non - metals.

Step3: Consider the state at room temperature

Among halogens in period 5, iodine ($I$) is a solid at room temperature.

Answer:

All four predictions, because they follow established periodic trends.