Science: Chapter 6


Terms in this set (...)

What are the 3 particles that make up an atom?
protons, neutrons, and electrons
Atoms are mostly empty space.
True/ False
Why are PROTONS, NEUTRONS, and ELECTRONS subatomic particles?
because they are each much smaller than the atom
What determines the properties of an atom?
The number of subatomic particles that are in an atom and the way the particles interact determines the properties of an atom.
What are the TWO particles that make up the nucleus of an atom?
protons and neutrons
What are protons?
Protons are positively charged particles of the nucleus.
Why did scientists make a new unit for the particles?
because the masses of the particles in the atom are so small
What is atomic mass unit (amu)?
(2 definitions)
key word: DESCRIBE
-The SI unit that describes the mass of a particle in an atom
-the unit of mass that describes the mass of an atom or molecule
What is the SI unit that describes the mass of a particle in an atom?
atomic mass unit
What is the mass of a proton?
1 atomic mass unit
What are neutrons?
Particles of the nucleus that have no charge.
Neutrons are smaller than protons.
-If false, then state the correct information.
-Neutrons are a little bit bigger than protons.
What is the mass of a neutron?
1 atomic mass unit
-same as the mass of protons
What are the most massive particles of an atom?
protons and neutrons
Why is the nucleus so dense?
bc the volume of the nucleus is so small
What are electrons?
Electrons are negatively charged particles of an atom.
Where are electron located?
They are located OUTSIDE of the nucleus in electron clouds.
How many electrons would it take to equal the mass of one proton?
What is the mass of an electron?
0 amu
Why is an atom considered "neutral"?
bc it has no overall charge
-The charges of protons and electrons are opposite but equal, so the charges cancel out.
What is an ion?
An ion is when an atom becomes a CHARGED particle. This happens when the numbers of protons and electrons become unequal.
How do you know if an atom is a positively-charged ion?
when the atom loses one or more electrons
How can you tell if an atom is a negatively-charged ion?
when the atoms gains one or more electrons
What is the nucleus of an atom?
The nucleus is the small, dense, positively charged center of the atom.
What determines the size of an atom?
the size of the electron clouds
What do neutrons do to protons?
It prevents the same number of protons from repelling from each other.
(same charged particles repel from each other)
An atom does not have to have the same number of protons and neutrons.
How can you tell which elements atoms represents?
the number of protons
What is the atomic number?
it is the number of protons in the nucleus of an atom
(it is the same for all atoms of an element)
What are isotopes?
Isotopes are atoms that have the same number of protons but different number of neutrons.
Why are atoms that are isotopes of each other always the same element?
bc they have the same number of protons
(number of protons always the same and determines element)
What happens when atoms have different number of neutrons?
They have different masses.
What is a RADIOACTIVE isotope?
A radioactive istotope is a type of isotope that is unstable and has a nucleus that changes over time
What do radioactive atoms do?
Radioactive atoms spontaneously fall apart after a certain amount of time and as they fall apart, they give off smaller particles and energy.
-Isotopes of an element share most of the same chemical and physical properties
-Different isotopes of an element behave similarly in chemical changes in your body.
How can you identify each isotope of an element?
by it's mass number
What is the mass number?
the sum of protons and neutrons in an element
Why are electrons not included in an atom's mass number?
bc their mass is so small that they have little effect on the atom's total mass
How do you identify a specific isotope of an element?
by writing the name of an element followed by a hyphen then the mass number
What is atomic mass?
(the actual mass)
the weighted average of the masses of all the naturally occurring isotopes of an element.
What are forces of an atom?
the pushes or pulls between objects
What are the four basic forces and their job?
gravitational force (pulls objects towards one another), electromagnetic force (holds electrons around nucleus/holds the opposite charges, pushes same charges), strong force (keeps nucleus in place), and weak force (for unstable atoms)
What do forces do to an atom?
the forces give an atom its structure and properties.
What determines the definite energy of electrons?
The electron's location around the nucleus
What does the energy in each electron do?
It keeps the atom in motion around the positive nucleus to which it is attracted.
What was Rutherford's contribution to the atom?
discovered that atoms are mostly empty space with a dense, positive nucleus.
(gold foil experiment)
Dalton's contribution to the atom.
-atomic theory
-how elements combine