Answer: 1=alkali metals
2= 1g/mL
3= Mercury
Explanation:
1=The alkali metals are six chemical elements in Group 1, the leftmost column in the periodic table. They are lithium (Li), sodium (Na), potassium (K), rubidium (Rb), cesium (Cs), and francium (Fr).
2=It's no coincidence that water has a density of 1. Density is mass divided by volume (ρ=m/v), and water was used as the basis for establishing the metric unit of mass, which means a cubic centimeter (1cm3) of water weighs one gram (1g).
So, 1g/1cm3 = 1 g/cm3, giving water its easy-to-remember density. However, water's exact density depends on both the air pressure and the temperature of the area. These variations in density are very slight though, so unless you need to know very exact calculations or the experiment takes place in an area with an extreme temperature/pressure, you can continue to use 1 g/cm3 for water density. You can look at the chart in the next section to see how water's density changes with temperature.
3=There are two elements that are liquid in room temperature.
Bromine (Br) melts at 265.9 K
Mercury (Hg) melts at 234.32 K - This is very interesting because all of Mercury's neighboring elements are solids at room temperature. Mercury is also much less reactive than Cadmium and Zinc which are directly above Mercury. Mercury doesn't conduct heat or electricity as well as other members of its group. Most metals are solids at room temperature because they share their valence electrons with surrounding metal atoms. However Mercury hangs onto its 6 valence electrons tighter than any other atom. Thus Mercury-Mercury bonds are weaker compared to other metal-metal bonds. It is also the only metal that doesn't form diatomic molecules in the gas phase. Since the amount of heat required to overcome the weak Mercury-Mercury bonds is lower, Mercury melts and boils at very low temperatures.
