use the following choices to answer #11 -20.

a. alkali metals b. alkalineearthmetals c. transition metals d. halogens e. noble gases

11. have 1 valence electron
12. includes fluorine, chlorine, bromine, and iodine
13. groups 3 - 12.
14. have7 valence electron
15. other than he, have 8 valence electrons
16. have 2 valence electrons
17. include silver, ag, gold, au, iron, fe, and copper, cu
18. include magnesium, mg, calcium, ca among others
19. cannot judge valence electrons by their group number(s)
20. sodium is classified as one of these

Alkali metals = have one valance electron

Alkaline earth metals = have two valance electrons

Transition metals = Group 3- 12.

Halogens = have seven valance electrons

Includes fluorine, chlorine, bromine, iodine, and iodine.

Noble gases = Other than He have 8 valance electrons.

Explanation:

Alkali metals = have one valance electron

Alkali metals are present in group one. All alkali metals have one valance electron.

Alkaline earth metals = have two valance electrons

Alkaline earth metals are present in group two. All alkaline earth metals have two valance electrons.

Transition metals = Group 3- 12.

Transition metals are present in middle of periodic table. Transition elements are present in group 3-12.

Halogens = have seven valance electrons

Halogens are present in group seventeen. All halogens have seven valance electrons. Halogens elements ,

Includes fluorine, chlorine, bromine, iodine, and iodine.

Noble gases = Other than He have 8 valance electrons.

Noble gases are present in group eighteen. All noble gases are inert.

the leaf is an organ of a typical plant, and the main functions are to complete photosynthesis and allow the plant to exchange gas, just like how we have the respiratory system. leaves have the stomata, which collects maintains co2 and o2 levels. this is necessary for cell metabolism. the leaf also collects sunlight using chloroplasts. succinctly, leaves own a pivotal role in sustaining plant life.