Atomic Theory
Why were Democritus's ideas not science?
They were not supported by experiment
The smallest piece of an element that still has the properties of that element is a(n) ____.
atom
The mass of a proton is measured in _____.
atomic mass units
Democritus believed that the universe is made of empty space and _____.
atoms
Aristotle believed that matter was _____.
capable of being broken down into infinitely smaller parts
A particle that moves around the nucleus is a(n) _____.
electron
The area around the nucleus where electrons are most likely to be found is called the _____.
electron cloud
The _____ of an atom is the number of neutrons plus protons.
mass number
A chemical symbol represents the ____ of an element.
name
Electrons have ____ charge.
negative
The nucleus of an atom is _____ charged.
positively
The number of which type of particle determines the identity of an element?
protons
What two subatomic particles are found in the center of an atom?
protons and neutrons
The atomic number of an element is the number of _____ of an atom of that element.
protons in the nucleus
Particles that make up protons and neutrons are called _____.
quarks
The atomic mass of an element is _____ of that element.
the average mass
What is the chemical symbol for carbon?
C
The first proposal that there is a smallest particle beyond which a substance cannot be divided was made by _____.
Democritus
Which scientist came up with the "plum pudding" model?
JJ Thomson
What 19th century scientist designed the atomic theory of matter?
John Dalton
Which of the following methods would be most useful for describing atoms?
Making a model
Who formed the first periodic table?
Mendeleev
What piece of technology was used to discover quarks?
A particle accelerator
A(n) _____ is matter that is composed of one type of atom.
element
An atom containing 6 protons and 6 electrons has a total charge that is _____.
neutral
Neutrons have _____ charge.
neutral
Is our modern atomic model 100% correct?
no
The middle of the atom is called the _____.
nucleus
The _____ is a chart created by scientists to organize the elements according to repeated changes of their properties.
periodic table
Protons have _____ charge.
positive
