Calcium (Ca) and diatomic oxygen (O2) combine to form calcium oxide (CaO). The data table below compares the properties of these substances. Calcium (Ca) Oxygen (O2) Calcium Oxide (CaO) Melting Point (°C) 842 −218.4 2613 Density (g/cm3) 1.54 0.00143 3.34 Appearance silvery-white metal colorless, odorless gas white, odorless powder What can be concluded from this data?

why is arctic sea ice important? arctic sea ice keeps the polar regions cool and moderate global climate. sea ice has a bright surface; 80 percent of the sunlight that strikes it is reflected back into space. as sea ice melts in the summer, it exposes the dark ocean surface.

practical process described pest part of scientific investigation.

because practical knowledge is powerful then therotical knowledge.

alkaline metals are lithium, sodium, rubidium, potassium, cesium and francium.

alkali metals have electronegativity from 0.7 to 1, lowest in periodic table of elements, which means that alkali metals (i group in periodic table) has positive oxidation number in compounds.

electronegativity is a chemical property that describes the tendency of an atom to attract a shared pair of electrons towards itself.

alkaline metals (far left in main group) have lowest ionizations energy and easy remove valence electrons,

for example, potassium is the alkali metal and has a single valence electron in the outer electron shell.

electron configuration of potassium is: ₁₉k 1s²2s²2p⁶3s²3p⁶4s¹.

they can not exist alone in nature, because they are very reactive.