The following is a column from the Periodic Table. The column shows one family of elements. Which of the following statements about the family of elements shown above is correct?

What is the atomic number of cesium (Cs)?

The elements in Family 1 of the Periodic Table are soft, silver-white metals. They are so soft that they can be cut with a knife. They are good conductors of heat and electricity. Because they each have only one valence electron, they bond readily with other substances. In fact, they are reactive that they are never found uncombed in nature. 

Based on the information above, which of the following statements about chemical families/groups are true?