| SODIUM | The most common alkali metal on Earth, comprising 2.8 percent of Earth's crust. It occurs abundantly in nature in compounds, especially in common salt. |
| ONE | Group for alkali metals on the periodic table |
| IRON | This metal makes up 5 percent of Earth's crust and is second in abundance to aluminum among the metals. The average quantity of this mineral in the human body is about 4.5 grams (about 0.004 percent), |
| STEEL | Most recycled metal on Earth |
| SNOW | Solid form of water that crystallizes in the atmosphere and falls to Earth. This material covers, permanently or temporarily, about 23 percent of Earth's surface. (4) |
| CAESIUM | Alkali metal that is the mos reactive of the elements; atomic no.55 (7) |
| SOLSTICE | The point when the Earth's axis is tilted most closely towards the sun; it occurs twice every year |
| SR | A soft silver-white or yellowish metallic element of the alkali metal group. |
| ELEMENTS | Halogens, lanthanides, noble gases, alkali metals ... general name for the 118 chemical substances arranged on the periodic table (8) |
| RINGOFFIRE | Pacific Ocean path that is home to seventy-five percent of Earth's volcanoes |
| PROFILE | Side view of a head; a biographical sketch; a vertical section of Earth's crust showing its strata; or, a user's personal page on social media (7) |
| BA | A silvery soft waxy metallic element of the alkali metal group. |
| NA | A silvery soft waxy metallic element of the alkali metal group. |
| LITHIUM | Soft silver-white univalent element of the alkali metal group (7) |
| FELDSPAR | Constituting around 50 per cent of Earth's crust, any of various rockforming minerals including amazonite, labradorite and moonstone (8) |
| METALS | General name for the elements forming part of Earth's crust including aluminium and iron (6) |
| SILICA | Compound that constitutes more than half the mass of Earth's crust |
| MASSIF | Block of Earth's crust lifted to form peaks of a mountain range (6) |
| RUBIDIUM | Soft silvery-white element of the alkali metals group similar to caesium and potassium, atomic no. 37 (8) |
| OCEAN | About 70 percent of Earth's surface |
