Chapter 3 - Atoms: The Building Blocks of Matter Flashcards
How did Mendeleev organize his periodic table?
Mendeleev organized the table in order of increasing mass.
How did Mosley reorganize the periodic table?
Mosley reorganized the table in order of increasing atomic number.
According to ________ ___, chemical and physical properties are a function of ______ _______.
According to periodic law, chemical and physical properties are a function of atomic number.
Who called nature’s basic particle an atom?
Democritus
What did Democritus believe in?
Democritus believed in a small indivisible particle?
Can the atom be divided?
Yes. The atom can be divided. (nuclear)
Aristotle did not believe in _____, he thought that all matter was ________.
Aristotle did not believe in atoms, he thought that all matter was divisible.
Until what century were the opinions about matter philosophical and not scientific?
18th century (1700s)
What three laws came about in the 1700s?
- Law of Conservation of Mass
- Law of Definite Proportions
- Law of Multiple Proportions
What does the Law of Conservation of Mass state?
Mass is neither created nor destroyed during ordinary chemical reactions.
What does the Law of Definite Proportions state?
A compound contains the same elements in the same proportions regardless of sample size or source of the compound.
What does the Law of Multiple Proportions state?
When element combines with another to form more than one compound, the mass ratios of the elements in the compounds are simple whole numbers of each.
What are Dalton’s five points to atomic theory?
- Matter is composed of atoms (extremely small particles).
- Atoms in one element are identical in size, mass, and other properties.
- Atoms can not be subdivided, created, or destroyed.
- Atoms of different elements combine as compounds in simple whole-number ratios.
- Atoms are combined, separated, and rearranged in chemical reactions not in nuclear reactions.
What did Thompson (1897) discover?
Thompson discovered that atoms are divisible and that electrons are present in different types of atoms.
How did Thompson come to this conclusion?
Thompson concluded that all cathode rays are composed of identical negatively charged particles called electrons–this was evidence for atom divisibility.
What type of model did Thompson make?
plum pudding model
Thompson believed that electrons were _________ _______, because they were balanced by a “pudding” of scattered positive charged protons and neutrons.
Thompson believed that electrons were electrically neutral, because they were balanced by a “pudding” of scattered positive charged protons and neutrons.
Millikan discovered that electrons are about ______ ___ _____ __ _ _______ ____.
Millikan discovered that electrons are about 1/2000 the mass of a hydrogen atom.
Who did the Gold Foil Experiment?
Rutherford
What is the Gold Foil Experiment?
Rutherford aimed positively charged alpha particles at gold foil.
What did Rutherford hypothesize the alpha particles would do in the Gold Foil Experiment?
He hypothesized that all of the alpha particles would pass through the foil and the hit the lead blocks behind it.
What happened in the Gold Foil Experiment?
1 in 8000 particles deflected back from the foil, which proved that most of an atom is empty space.
What did Rutherford believe caused the deflection?
Rutherford believed that small bundles of matter with a positive charge caused the deflection (“nucleus”).
What important discovery did Rutherford make?
Rutherford discovered that the volume of the nucleus was very small compared to the total volume of an atom.
