Chapter 4- Structure of an Atom

neutron

0 charged sub-atomic particle located in the nucleus and responsible for other half of mass. relative mass is 1 amu

atomic mass unit (amu)

1/12th the mass of a carbon-12 atom.

Dalton's atomic theory

All matter is made of atoms. Atoms are indivisible and indestructible. 2) All atoms of a given element are identical in mass and properties 3) Compounds are formed by a combination of two or more different kinds of atoms. 4) A chemical reaction is a rearrangement of atoms.

isotopes

Atoms with the same number of protons but different numbers of neutrons

Aristotle

Believed that matter was made up of earth, air, fire, and water. Didn't believe in empty spaces. Views lasted 2000

Ernest Rutherford

Discovered protons and empty space of atom using alpha particles. Help create atomic model with proton containing nucleus and empty space. Also, majority of atom's mass is in the nucleus

quantum number

Each orbit, around the nucleus, was given a number for energy levels

Gold Foil Experiment

Experiment in which alpha particles were beamed towards gold foil conducted by Ernest Rutherford

Plum Pudding model

JJ. Thomson's chocolate chip cookie model of the atom after discovering electron. Electrons are chips. dough is positive.

ground state

The lowest allowable energy state of an atom

Robert Millikan

Use oil drop apparatus to determine charge of electron and mass

cathode ray

an electric charge is applied, a ray of radiation travels from the cathode to the anode

Bohr's Model of the atom

an electron moves around the nucleus only in certain allowed circular orbits.

JJ. Thomson

discovered electron using cathode ray tube experiment

James Chadwick

discovered the neutron and the atom's additional mass in the nucleus.

atomic mass

element is the weighted average mass of the isotopes of that element.

Democritus

first person to propose the idea that matter was not infinitely divisible, but made up of individual particles called atomos. Believed in empty space around atoms, atoms indivisible, indestructible, and different kinds with different properties and shapes

orbital shells

location of where electrons can be placed

atomic number

number of protons in the nucleus of an atom identifies the element

Sub-atomic particle

part of the building blocks of atoms, electrons, protons and neutrons

electrons

particles carrying a negative charge of 1- and have mass of 9.1x10^-28 g or 1/1840 of Hydrogen , occupy space around nucleus

proton

positively charged sub-atomic particle located in the nucleus with 1+ charge, relative mass is 1 amu

nucleus

proton and neutron containing center of an atom

atom

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

quantum

the minimum amount of energy that can be gained or lost by an atom.

mass number

the sum of the protons and neutrons in the nucleus