Chapter 3 Flashcards
All atoms of a given type are ________ to each other.
similar
What 3 physical characteristics of all atoms are known with a great deal of certainty?
size, shape, and mass
Atoms are incredibly small but they differ in _____ and _______.
size and mass
If atoms can break apart, they must be made of something ______ than an atom.
smaller
___________ are small particles which serve as fundamental building blocks for all atoms.
Subatomic particles
All atoms are made up of very small particles called ______ _______.
subatomic particles
_______ have a negative charge.
Electrons
_______ have a positive charge.
Protons
______ have NO charge.
Neutrons
The subatomic particles can be distinguished from each other based on their _____ and ______.
charge and size
What is the charge associated with an electron?
negative
Why did it take so long to find the neutron?
Neutrons don’t have a formal charge
What is the overall charge of an atom?
neutral
In order for an atom to have a neutral charge, it must contain the same number of _____ and _______.
protons and electrons
Electrons travel from the ______ electrode and move toward the ______ one.
negative (cathode);
positive (anode)
Robert Millikan was able to calculate the _________ of an electron.
charge / mass ratio from the experimental data
Protons move toward the ______ electrode.
negative
Protons are approximately ____ more ______ than electrons.
1800 times more massive
What did scientists NOT KNOW about atoms and subatomic particles after the discovery of radioactivity?
They didn’t know how they were organized within the structure and they didn’t know about neutrons.
What is the calculated mass, in grams, of a proton?
1.673 x 10^-24g
Ernest Rutherford proposed that most of the mass of an atom was found where?
in the nucleus
Since the total mass of all the electrons in an atom is negligible, the mass of an atom is determined by the number of ____ and ______.
protons and neutrons
Protons and neutrons are much ______ than electrons.
heavier
According to the modern atomic model, most of the volume of an atom is ______ space.
empty
The volume or size of an atom is basically determined by the movement of ______.
electrons
The total mass of an atom is basically found in the _____ of an atom.
nucleus
The size or volume of an atom is determined by the ________.
area swept out by the electrons, which is mostly empty space.
TRUE or FALSE:
Large atoms are always more massive than small ones.
false
The nucleus of an atom has a net ______ charge.
positive
The overall charge of an atom is ______.
neutral
The mass of an atom is determined by the _______ and the size of the atom is determined by the ______.
nucleus;
electrons and their movement
The relative number of _____________ accounts for the observed differences in atoms.
subatomic particles
An uncharged atom must always have equal numbers of _____ and ______.
protons and electrons
Whenever an uncharged atom has one more proton than another atom of a different type, it must also have one more _______.
electron
Carbon atoms have 6 protons, therefore they must have _____ electrons.
6
If two atoms represent two different elements, they must have a different number of ______.
protons
The ________ is the counted number of protons in the nucleus of an atom and is a unique identifier for each element.
atomic number
The atomic number is a description of the number of _______ in the nucleus of at atom.
protons
If 2 atoms have different atomic numbers, they must be atoms of different _____.
elements
An element can be _______ by it’s atomic number.
identified
If Uranium if the element 92, how many electrons are found in a Uranium atom?
92
TRUE or FALSE:
An atomic number of 2.5 is an allowed value for certain atoms.
false
The ________ of an atom is a whole number that describes the total number of protons and neutrons in the nucleus of an atom.
mass number
The mass number is also referred to as:
the A number
The sum of protons and neutrons in a nucleus is referred to as the ____________.
mass number
What is the mathematical equation to find the mass number of an element?
mass number (A) = number of protons (p) + number of neutrons (n)
Only two numbers are needed to specify the complete subatomic composition of an atom. These two numbers are the _____ and ____ number.
mass and atomic