Science - Chapter 4 Lesson 1 - Test 11/21/13 Flashcards
What did the Greek philosopher Democritus propose about matter?
That matter was formed of small pieces that could not be cut into smaller parts.
Democritus used the word atomos, which means ______.
Democritus used the word atomos, which means “uncuttable”.
In modern terms, an atom is the ______ particle that can be considered an element.
In modern terms, an atom is the smallest particle that can be considered an element.
_________ inferred that atoms had certain characteristics.
John Dalton inferred that atoms had certain characteristics.
What was John Dalton’s theory about the characteristics of atoms?
He thought they were like smooth, hard balls that could not be broken into smaller pieces.
Who discovered that atoms contain negatively charged particles called neutrons?
J.J. Thomson
J.J. Thomson said that in addition to the neutrons, atoms must also contain some sort of _________, which would balance out the negative charge of the electrons.
positive charge
How did J.J. Thomson describe an atom that had electrons?
scattered throughout a ball of positive charge
Give an example of J.J. Thomson’s description of an atom with electrons.
seeds in a watermelon
Rutherford’s _________ showed that most of the particles passed straight through the foil with little or no deflection.
Rutherford’s gold foil experiment showed that most of the particles passed straight through the foil with little or no deflection.
Like charges ______ each other.
Like charges repel each other.
What did Rutherford infer about an atom’s positive charge?
An atom’s positive charge must be packed with a small region in its center, called the nucleus.
The positively charged particles in an atom’s nucleus are _____.
The positively charged particles in an atom’s nucleus are protons.
Give an example of how a nucleus looks in an atom.
- peach
- cherry
When did Niels Bohr revise the atomic model?
1913
