Ch. 2 The Structure of Matter Flashcards
Break down the word atom
a (not) + temon (cut) (indivisible)
How many elements have been identified?
118
How many elements are natural and how many artificially produced?
92 natural and 26 artificial
An atom is…
the smallest particle of matter that has the properties of an element
Whose work brought about the first periodic table of elements?
Dmitri Mendeleev
Where is the atomic # and where is the elemental mass?
Atomic # is above the element symbol and the atomic mass is below.
groups are in….
columns
How are elements in groups similar?
They react chemically in a similar fashion and have similar physical properties
Elements in group I are all soft metals (alkali metals) and combine readily with oxygen and react violently with water except…
Hydrogen
What are the elements in group VII called?
halogens
What are the elements in group VIII called?
noble gases
How are elemental groupings determined?
By the placement of electrons in each atom
Cathode rays are also called…
electrons
What type of charge are electrons?
negatively
What is the newer model of the atom called?
quantum chromodynamics (QCD)
Describe the Bohr Atom
A small, dense, positively charged nucleus surrounded by negatively charged electrons that revolve in fixed, well-defined orbits about the nucleus.
In a normal atom, what is equal to what?
the number of electrons is equal to the number of positive charges in the nucleus
What is an atom smasher?
a particle accelerator
What are nucleons?
protons and neutrons that are composed of quarks that are held together by gluons
What are the primary constituents of an atom in radiologic science?
electron, proton and neutron
What are the fundamental particles of radiology?
electron, proton, and neutron
What determines how an atom will interact?
The arrangement of electrons around the nucleus.
Electrons are very small particles that carry…
one unit of negative electric charge
What is the mass of an electron?
9.1 x 10^-31
How is the mass of an atom expressed?
in atomic mass units (amu)
When precision is not necessary, what is used instead of the amu?
the atomic mass number, which is always a whole number
Where are nucleons?
In the nucleus
How many different types of nucleons are there and what are their names?
2 types; protons and neutrons
Describe the mass of protons and neutrons.
They have nearly 2000 times the mass of an electron
Which is heavier, a proton or neutron?
Neutron by 0.002 kg
What is the primary difference between a proton and neutron?
electric charge
What is the electric charge of a proton and of a neutron?
a proton has one unit of positive electric charge and a neutron carries no charge
An atom is mostly…
empty space
What contains nearly all the mass of an atom?
the nucleus
Electron orbits are called..
shells
What do the shells do?
The arrangements of the shells helps reveal how an atom reacts chemically, or how it combines chemically with other atoms to form molecules
A neutral atom has the same….
number of electrons in orbit as protons in the nucleus
What part of the nucleus in a neutral atom determines the chemical behavior of an atom?
the number of protons
What determines the chemical element of an atom?
the number of protons
What are isotopes?
Atoms that have the same number of protons but differ in the number or neutrons
How many protons and electrons are in an atom of hydrogen?
1 and 1
What do the shells represent?
different electron binding energies or energy levels
When is the binding energy of an electron the greatest?
the closer it is to the nucleus
In what state are atoms electrically neutral?
in their natural state their charge on the atom is zero
The total number of electrons in the orbital shells equals what?
the number of protons in the nucleus
When is an atom ionized?
If an atom has an extra electron or has had an electron removed
The number of neutron is always
greater than the number of protons
The maximum number of electrons that can exist in each shell _______ with the distance of the shell from the nucleus.
increases
What is the formula that calculates the electron limit per shell?
2n^2
What is the principal quantum number?
the shell number n
The number of electrons in the outermost shell is:
- Equal to its group in the periodic table
2. Determines the valence of an atom
The number of the outermost electron shelll is:
equal to its period in the periodic table