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The law of fixed composition

Portrait of John Dalton

Quiz: Dalton's Atomic Theory

1. Dalton suggested that atoms were indestructible and unchangeble to explain:
why mass is conserved in chemical reactions
why compounds combine in fixed weight ratios in chemical reactions
why elements combine in fixed weight ratios to form compounds
why elements are characterized by the mass of their atoms
2. When elements react, their atoms combine in:
a simple whole number ratio (unique for each pair of elements)
simple whole number ratios (more than one possible)
arbitrary proportions
1:1 ratios
3. Dalton viewed chemical change as:
creation and destruction of atomsa nuclear exchange
a transfer of protonsa transfer of electrons
a change of atoms from one type into anothera rearrangement of atoms
4. Hydrogen combines with oxygen in a 1:8 weight ratio to form water. If every molecule of water contains two atoms of hydrogen and one atom of oxygen, an atom of oxygen must weigh:
1/16 times the mass of a hydrogen atom8 times the mass of a hydrogen atom
1/8 times the mass of a hydrogen atom16 times the mass of a hydrogen atom
5. 1.008 grams of hydrogen combines with 35.453 g of chlorine to form 36.463 g of a pure compound (hydrogen chloride). Dalton's explanation for this experimental fact might be:
this is a simple mixture of elements because the ratio isn't a whole number ratio
hydrogen and chlorine atoms aren't created or destroyed in the process so the reactant mass is the same as the product mass.
one atom of hydrogen combines with 35.453 atoms of chlorine in this reaction
hydrogen and chlorine atoms always combine in a 1:35 ratio.
chlorine accepts hydrogen's electron to form polar covalent hydrogen chloride

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

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Last Revised 02/23/18.URL: http://antoine.frostburg.edu/chem/senese/101/atoms/dalton-quiz.shtml