Atoms 101
Rutherford discovered that most of an atom is ....
a. positive particles
b. empty space
c. negative particles
empty space
What subatomic particles have about the same mass?
protons and neutrons
According to Bohr, electrons can become ______ when they absorb energy.
What is excited?
Which nuclear process happens on the sun?
fusion
How do you figure out the # of neutrons?
atomic mass - protons
What are the 3 subatomic particles that make up an atom?
protons, neutrons, and electrons
What is the charge of a proton?
(+ 1) positive
Sulfur has a -2 charge, this means it ....
What is gained 2 electrons?
Which type of nuclear process that causes a chain reaction?
fission
If a sodium ion has a +1 charge, what does this mean?
it lost 1 electron
What subatomic particle determines the identity of an atom?
protons
What is the charge of a neutron?
no charge / neutral
How many electrons can fit on first energy level?
What is 2?
This type of decay can be block by paper or skin.
alpha decay
What is the term used to describe electrons in their normal state?
ground state
What particle(s) is found is the nucleus?
protons and neutrons
What is the charge of an electron?
(- 1) negative
How many electrons can fit on the 2nd, and 3rd, energy levels for our Bohr models?
What is 8?
What is the time it takes for half of a sample to decay.
half-life
After 1 half-life, what % of a sample remains?
50%
How do you figure out the number of protons in an element?
look at the atomic number
where is most of the mass in an atom?
What is the nucleus?
List 1 reason valence electrons are important.
involved in bonding
determines reactivity of an element
If Technetium-99 has a half-life of 6 hours, after 18 hours, how many half-lives have passed?
3
After 2 half-lives, what % of a sample remains?
25%