What is the main reason for the periodic trends in atomic size across a period? (Variant 7)Correct Answer: Increase in nuclear charge ! Other People SaidIncrease in the number of energy levels: 94 Increase in nuclear charge: 1000 Increase in electron repulsion: 108 Next Question: What is the main reason for the periodic trends in atomic size across a period? (Variant 8)Increase in the number of energy levelsIncrease in nuclear chargeIncrease in electron repulsion