What is the main reason for the periodic trends in atomic size across a period? (Variant 8)Correct Answer: Increase in nuclear charge ! Other People SaidIncrease in the number of energy levels: 93 Increase in nuclear charge: 1001 Increase in electron repulsion: 85 Next Question: What is the main reason for the periodic trends in atomic size across a period? (Variant 9)Increase in the number of energy levelsIncrease in nuclear chargeIncrease in electron repulsion