Chapter 2 vocab Flashcards
(67 cards)
What did dalton do
bring back the idea of the atom. created “Daltons Atomic Theory” based on 3 laws
what are the 3 laws dalton based his theory on
law of constant composition
law of conservation of mass
law of multiple proportions
what does the law of constant composition mean
that there is the same number of atoms in any sample. every grain of salt is NaCl. discovered by joseph proust
what does the law of conservation of mass mean
the total mass of substances present at the end of a chemical process is the same as the mass in the beginning
what is the law of multiple proportions
if i make a new compound I can only add or subract by a whole atom, not half at atom
4 postulates of daltoms atomic theory
- each element is composed of small particles called atoms
- all atoms of a given element are identical, but the atoms of one element can differ from t he atoms of other elements
- atoms of one eleemtn cant be changed into atoms of a diff eleement by chemical reactions, elements cant be created or destroyed
- compounds are formed when atoms of more than one element combine
who tested the electon? and what?
JJ thomson used cathode rays to discover charge to mass ratio of 1.76E^8 coulombs/gram
millikan disovered charge and mass of an electron (the oil drop)
what is radioactivity
spontaneous emission of high radiation by an atom
who studied radioactivity
marie and pierre curie. and henri becquerel observed it
what did radioactivity prove
led to a discovery that an atom had subatomic particles and energy
Three types of radiation?
a` positive
a ^ negative
a~ no charge
how was the nucleas discovred
shot positive particles at a thin sheet of gold foil to observe the pattern of the particles
What is most of an atom?
empty space
what is in a nucleus
protons and neutrons
Proton mass
1.0073 amu
Nuetron mass
1.0087 amu
Electron mass
close to 0 (5.486E^-4 amu)
What is an atomic number
the number of protons in the nucleus
top left of an element symbol resembles what
the mass number
bottom left of an element symbol resemles what
the atomic number
how to get mass #
protons AND neutrons
how to get atomic #
protons OR electrons
What does isotope mean
atoms of the same element with different masses, meaning different # of neutrons
Amu means?
Atomic mass unit
