While Democritus proposed the philosophical concept of the atom in ancient Greece, John Dalton formulated the first scientifically based atomic theory in 1803. His theory stated that elements are composed of indivisible atoms, atoms of the same element are identical, and compounds form from atoms combining in fixed ratios.
Explanation:
Down Group 1 (Li → Fr), atomic radius increases due to addition of electron shells. Ionization energy and electronegativity decrease. Reactivity with water increases because the outer electron is more easily lost. Density generally increases, melting/boiling points decrease. Cesium and francium are most reactive. The increase in radius is due to principal quantum number increase.
Explanation:
Diammonium phosphate (DAP) is (NH₄)₂HPO₄. It is produced by reacting ammonia with phosphoric acid: 2NH₃ + H₃PO₄ → (NH₄)₂HPO₄. It contains 18% N and 46% P₂O₅. Monoammonium phosphate (MAP) is NH₄H₂PO₄. Ammonium sulfate is (NH₄)₂SO₄. Triammonium phosphate is unstable. DAP is widely used as a starter fertilizer.
Explanation:
Charles' law: V ∝ T (Kelvin). So at constant P and n, V/T = constant. If temperature is in Celsius, proportionality is not direct because zero Celsius is not absolute zero. Absolute zero (0 K = -273.15°C) is the theoretical temperature at which volume becomes zero. A graph of V vs T (K) is a straight line through origin.
No comments yet. Be the first to start the discussion!