Unit 3 test Flashcards
isotopes
atoms of the same element with a different number of neutrons
ion
atom with charge (when the element symbols shows there is either -1, or +3)
anion
negatively charged ion (-2)
What is responsible for most of the mass of an atom and what is responsible for most of the volume of an atom?
nucleus is responsible for most mass and electron cloud is responsible for volume
cation
positively charged ion (+3)
democritus
first to go against belief and propose all matter was composed of indivisible particles he call “atomos”
democritus’s 3 core beliefs
- everything is composed of atoms which are physically indivisible
- atoms are indestructible and constantly moving
- there is empty space between atoms
who developed the law of definite proportions
proust in 1700s
the law of definite proportions
regardless of the amount used, a chemical compound is always composed of the same elements in the same proportions. elements combine in fixed proportions based on their mass
who came up with the law of conservation of matter
lavosier
the law of conservation of matter
in any chemical reaction the mass of the reactants always equals the total mass of the products
who developed the law of multiple proportions
dalton - also said there was more then one mass ratio
the law of multiple proportions
chemical compounds always contain the same proportions of elements by mass
Daltons atomic theory
1.all matter is composed of extremely small particles called atoms
2. atoms of a given element are identical. Atoms of different elements are different
3. atoms cannot be created, destroyed, or subdivided
4. atoms of different elements can combine in single whole number ratio
5. in chemical reactions, atoms are rearranged
john dalton
believed that an atom is like a solid ball
JJ Thompson
used cathode ray tube to discover there were negative particles in the atom called elcetrons
- made the plum pudding model
who discoverd the charge of an electron
milikan - preformed oil drop expirement
Rutherford
wanted to determine how the rest of the mass and charge of an atom was distributed - bomabrded gold foil with alpha particles - nucleus model
who and when the planatary model
bohr 1913
plantary model
related atomic structure to wavelengths of light that an electron emits when heated
current model of the atom
quantum mechanical model developed by edwin schrodinger 1926
quantum mechanicle model
says electrons do not travel in fixed orbits around the nucleus but in waves
who discoverd neutron
chadwick 1932 - no charge equal mass to proton
what is responisble of an atoms charge
electron
