Atomic Theory and Structure Early Ideas about Matter: From Democritus to Dalton by Anthony Carpi, Ph.D. Reading Quiz Teach with this Joseph Priestley discovered: mercury hydrogen America oxygen Who proposed the first atomic view of matter? Lavoisier Empedocles Democritus Priestley The ancient Greeks believed that matter was composed of four basic materials. Which one of the following was not one of the four? earth fire gold water Which one of the following is not part of Dalton's atomic theory? Atoms of the same element have the same chemical properties Matter is composed of atoms Atoms of different elements have different properties Atoms change into other atoms in chemical reactions A substance that cannot be broken down by chemical means into simpler substances is called a(n): solid element compound mixture Which one of the following statements concerning the relationship between the number of elements and the number of compounds is correct? The number of elements is much larger than the number of compounds The number of elements must equal the number of compounds The number of elements and compounds is approximately the same The number of compounds is much larger than the number of elements The number of known elements at this time is approximately: 50 116 100 infinite Which one of the following symbols represents an element? CO He HF NO Which one of the following symbols represents a compound? Co CO2 He N Substances A and B combine chemically to form C. Substance C must be: an element a solution a compound a mixture Although all parts of Dalton's atomic theory are important, which one of the postulates is crucial to explain the observations summarized by the Law of Definite Proportions? Atoms are very small. Atoms of the same elements have the same properties Matter is composed of atoms Atoms chemically combine with other atoms in fixed, whole-number ratios No matter how much extra oxygen is available, 12 grams of carbon always combines with 32 grams of oxygen. This best illustrates the law of: Multiple Proportions Definite Proportions Conservation of Energy Conservation of Mass 12 grams of carbon react with 32 grams of oxygen to form exactly 44 grams of carbon dioxide. This is a good example of: Democritus' theory Priestley's experiments the Law of Conservation of Mass the Law of Multiple Proportions Who first proposed the Law of Definite Proportions? Empedocles Proust Dalton Priestley Score Quiz