Chemistry - Chapter 4&5

Democritus

lived from 460 BC- 370 BC and was among the first to suggest the idea of atoms

atom

smallest particle of an element that retains the properties of that element

why did J.J. Thompson reason that electrons must be a part of thee atoms of all elements

charge-to-mass ratio of electrons was the same, regardless of the gas used

what does the mass of a neutron equal

the mass of a proton

all atoms are

neutral, with the number of protons equaling the number of electrons

nucleus of an atom is

the central core and is composed of protons and neutrons

protons

the atomic number of an element is the total number of these particles

element has an atomic number of 76. the number of protons and electrons in a neutral atom of the elements are

76 protons and 76 electrons

mass number

the sum of protons and neutrons in an atom

isotopes of the same element have different

numbers of neutrons

how many protons and electrons does In have

49 protons, 49 electrons

how many protons, electrons, and neutrons does an atom with atomic number 50 and Mass number 125 have

50 protons, 50 electrons, 75 neutrons

how is the number of neutrons in the nucleus of an atom calculated

subtract the number of protons from the mass number

atomic mass

weighted average of the masses of the isotopes of an element

what is necessary to calculate the atomic mass of an element

the masses of each isotope of the element

the principal quantum number indicates what property of an electron

energy level

what is the max number of d orbitals in a principal energy level

5

what does the letter “p”in the symbol 4p³ indicate

orbital shape

quantum mechanical model of the atom

involves the probability of finding an electron in a certain position

frequency

number of waves that pass a point per second

quantum

the energy needed to move an electron from one energy level to another

Pauli Exclusion Principle

to occupy the same orbital, two electrons must have opposite spins; that is, the electrons’ spins must be paired

Hund’s Rule

orbitals of equal energy are occupied by one electron before any orbital is occupied by a second

photons

quanta of light

max number of orbitals in p sublevel

3

Hertz

what the frequency of electromagnetic radiation is measured in in SI