2. Hydrogen combines with fluorine in a 1:19 weight ratio to form hydrogen fluoride. If every molecule of hydrogen fluoride contains one atom of hydrogen and one atom of fluorine, an atom of fluorine must weigh:

	1/38 times the mass of a hydrogen atom		19 times the mass of a hydrogen atom
	38 times the mass of a hydrogen atom		1/19 times the mass of a hydrogen atom

3. When elements react, their atoms combine in:

	arbitrary proportions
	triplets
	1:1 ratios
	simple whole number ratios (more than one possible)
	a simple whole number ratio (unique for each pair of elements)
	pairs

4. Dalton suggested that atoms were indestructible and unchangeble to explain:

	why elements combine in fixed weight ratios to form compounds
	why elements are characterized by the mass of their atoms
	why compounds combine in fixed weight ratios in chemical reactions
	why mass is conserved in chemical reactions

5. Hydrogen combines with nitrogen in a 3:14 weight ratio to form ammonia. If every molecule of ammonia contains three atoms of hydrogen and one atom of nitrogen, an atom of nitrogen must weigh:

	3/14 times the mass of a hydrogen atom		14 times the mass of a hydrogen atom
	3 times the mass of a hydrogen atom		14/3 times the mass of a hydrogen atom

Dalton's Atomic Theory
Page 1: Introduction
Page 2: Dalton's assumptions Five steps forward and one step back.
Page 3: Atoms in compounds An "invisible hand" fixes atom ratios in compounds
Page 4: Atoms in reactions Dance of the atoms
Page 5: Learning check Take a quiz on Dalton's Atomic Theory
Page 6: References and resources

General Chemistry Online! Quiz