Chemistry- Chapter 3 Voceb

Law of Conservation of Mass

law that states the mass cannot be created or destroyed in ordinary chemical and physical changes

Law of Definite Proportions

law that states that a chemical compound always contains the same elements in exactly the same proportions by weight or mass

Law of Multiple Proportions

law that staes that when two elements combines to form two or more compounds, the mass of one element that combines with a given mass of the other is in the ratio of small whole numbers

Atom

smallest unit of an element that maintains the chemical properties of that element

Nuclear Forces

interaction that binds protons and neutrons, protons and protons, neutrons and neutrons together in a nucleus

Atomic Number

number of protons in the nucleus on an atom; atomic number is the same for all atoms of an element

Isotope

atom that has the same number of protons as other atoms of the same eement do but that has a different number of neutrons

Mass Number

sum of the protons and neutrons that make up the nucleus of an atom

Nuclide

atom that is identified by the number of protons and neutrons in its nucleus

Atomic Mass Unit

sum of the protons and neutrons that make up the nucleus of an atom

Average Atomic Mass

weighted average of the masses of all naturally occurring isotopes of an element

Mole

SI base unit used to measure amount of a substance whose number of particles is the same as the number of atoms of carbon in exactly 12g of carbon-12

Avogadoro’s Number

6\.02 x 10^23, the number of atoms or molecules in 1 mol

Molar Mass

mass in grams of 1 mol of a substance

Henry Moseley

atomic number; working with hydrogens

Millikan

charge and mass of electrons; oil drop experiment

JJ Thomson

electron; cathode ray tube

Rutherford

nucleus and proton; gold foil expirement

Chadwick

neutron

Leucippus

first to propose concept of atoms

cathode ray tube

vacuum tube painted florsescent through which electrons are passed

Dalton’s atomic theory

1. matter is composed of extremely small particles called atoms

2. atoms in a given element are identical

3. atoms cannot be subdivided, created, or destroyed

4. atoms combine into whole number ratios to form compounds

5. chemical reactions, atoms are separated, combined, or rearranged

atomic mass unti

based on carbon-12

nucleus

all mass, little volume

electron cloud

all volume, little mass