How did early chemists determine which substances were elements?

a. by observing chemical reactions

b. by finding the atomic mass

c. by counting neutrons

d. by counting protons

Do you add water to acid or acid to water?

How many helium atoms are in a helium blimp containing 498 kg of helium?

Give the ground-state electron configuration for silicon (SiSi) using noble-gas shorthand. Express your answer in condensed form as a series of orbitals. For example, [Ar]4s23d8[Ar]4s23d8 would be entered as [Ar]4s^23d^8.

Water Wood Neon gas Arrange the substances in the table from the MOST to the LEAST ordered particle arrangement. A) wood, water, neon gas B) wood, neon gas, water C) water, wood, neon gas D) water, neon gas, wood

How many equivalent resonance forms can be drawn for so2 without expanding octet on the sulfur atom? (sulfur is the central atom.

Identify the spectator ions in the following complete ionic equation. 2k (aq) s2 - (aq) pb2 (aq) 2no-3 (aq) →pbs (s) 2k (aq) 2no-3 (aq) express your answers as ions separated by a comma.

4. A bird left its post and flew in a triangular path. It flew 21 yards south, 72 yards east and 75 yards diagonally to end back at the post. Is it a right triangle?

Condension occurs in the inside of your windows in Winters, why?

How can you use Hess's law to determine a reaction's enthalpy?

7. How much energy in KJ is released when 15.0 g of steam at 100.0 degrees Celsius is condensed and then frozen to ice at 0.0 degrees Celsius?