Element $X$ forms a chloride with the formula $XCl_2$,which is a solid with a high melting point. $X$ would most likely be in the same group of the Periodic Table as

Name two elements you would expect to show chemical reactions similar to magnesium. What is the basis for your choice?

What were the limitations of Newlands' Law of Octaves?

What property do all elements in the same column of the Periodic Table as fluorine have in common?

Nitrogen (atomic number $7$) and phosphorus (atomic number $15$) belong to group $15$ of the Periodic Table. Write the electronic configuration of these two elements. Which of these will be more electronegative? Why?

Which element has
$(a)$ a total of three shells,with four electrons in its valence shell?
$(b)$ a total of two shells,with three electrons in its valence shell?
$(c)$ twice as many electrons in its second shell as in its first shell?