Fast fast fast 13. an element whose nucleus breaks down is
-plutonium
-oxygen
-neon
-allotrope
23. choose all that apply. What [Na]+ forms with [Cl]-
-sodium chloride
-ionic bond
-covalent bond
-table salt
12. the most common element in the human body is what?
-hydrogen
-phosphorus
-calcium
-oxygen
4. what element never combines in nature?
-nitrogen
-hydrogen
-xenon
-carbon
17. all of __ are radioactive and rarely found on nature
-noble gases
-metalloids
-actinides
-alkali metals
2. why is hydrogen grouped with alkali metals?
-it has one electron in its outer energy level
-it is a gas
-it is a Metal
-it does not readily form compounds