what is period 2 group 7 element symbol

2.42 What is a period in the periodic table? From what does it derive its name?

Is hydrogen metal nonmetal metalloid

Question is attached

Which group(s) in the periodic table contain only nonmetals?

What is the formula of cadmium oxide?

57. Which elements are alkaline earth metals?(a) sodium(b) aluminum(c) calcium(d) barium(e) lithium

Elements in Group 7A are known as the A) alkaline earth metals B) alkali metals C) chalcogens E) noble gases D) halogens

An electrical charged atom or group of atoms. What is it

Decide which element probably forms a compound with hydrogen that has a chemical formula most and least similar to the chemical formula of the compound formed by hydrogen and fluorine. Comparing chemical formula of compound formed with hydrogen: chlorine sulfur strontium selenium most similar to fluorine least similar to fluorine