Ch 3 Flashcards
What does mass number tell you?
Number of protons + neutrons
Atomic number tells you..
Where is it?
Number of protons
Upper left corner
Where are protons neutrons and electrons
Protons and neutrons are in nucleus and electrons are on outside
What is the relationship between protons and neutrons?
Same number of everything, different charges
What is on bottom left corner of an element?
Average atomic mass
What is in upper right?
Numbers of electrons, in circle
Mendeleev
Used playing cards, put them in order
Democritus
Greek, came up with idea of the atom
John dalton
Came up with modern atomic theory,
Thompson
Discovered the electron
Law of conservation of mass
States that during a chemical reaction the total mass of the products must be equal to the total mass of the reactants. ( no matter is created or destroyed during chemical reactions)
Law of definite portions
States that a given chemical compound always contains the same elements in the exact same proportions by mass.
Law of multiple proportions
Whenever the same two elements form more than one compound, the different masses of one element that combine with the same mass of the of the element are in the ratio of small whole numbers.
Daltons atomic theory
- All matter is composed of atoms
- Atoms of the same element are identical
- Atoms of different elements can chemically combine with one another to form compounds.
- Chemical reactions can be defined as the separation, combination, or rearrangement of atoms.
Atom
Smallest particle of an element
Cathode ray tube
An electric current is passed through gasses at a low pressure ( JJ Thompson used it)
Electrons
Negatively charged particles present In all atoms
Robert Millikan
Determined the charge of a single electron (used oil drop experiment)
Eugene Goldstein
Discovered evidence for the proton
Proton
Positively charged particle present in all atoms
Neutron
Particle with no charge with mass the same as a proton
Nucleus
Tiny, dense, central core of the atom and is composed of protons and neutrons.
Mass number
Total number of protons and neutrons in an atom
Isotopes
Atoms with the same atomic number but different mass number because of a change in the number of neutrons.