Gold has a very high density of about 19.32g/cm^3 while Aluminum has a low density of 2.7 gm/cm^3 which means gold can pack more amount of matter in a comparatively small space as compared to Aluminum.
Answer is: Cl and Na.
sodium and chlorine are in third period and they have very different properties. Sodium is solid metal and chlorine is gaseous nonmetal.
They form compound NaCl (Sodium chloride), because sodium lost one valence electron and form cation Na⁺, chlorine gain one electron and form anion Cl⁻.
Electron configuration of sodium atom: ₁₁Na 1s² 2s² 2p⁶ 3s¹.
Electron configuration of chlorine atom: ₁₇Cl 1s² 2s² 2p⁶ 3s² 3p⁵.
Other examples are metal-metal pairs and they do not form cation and anion.
One of the two products of this reaction is carbonic acid (H2CO3), which immediately forms water and the gas you identified after exposure to the flaming and glowing splints. Write a balanced equation showing the decomposition of carbonic acid.
24= y2k* - 2x H202 grams in mass
