chp 4 atom models

1. all elements are composed of tiny indivisible particles called _________ 2. atoms of the same element are _____. the atoms of any one element are ______ from those of any other element 3. atoms of __________ elements can physically mix together or can ____________ combine in simple whole-number ratios to form __________ 4. Chemical reactions occur when atoms are ________, __________, or __________. Atoms of one element are ____ changed into atoms of another element in a chemical reaction.

1. atoms 2. identical different 3. different chemically compunds 4. seperated joined rearranged never

by using experimental methods, _______ transformed ________ ideas on atoms into a scientific theory

Dalton Democritus's

an _____ is the smallest particle of an element that retains its identity in a chemical reaction

atom

to calculate the ________ _________of an element, multiply the mass of each isotopse by its natural abundance, expressed as a decimal, and then add the products. and divide by 100

atomic mass

an ________ ___________ _________ is defined as one twelfth of the mass of a carbon-12 atom

atomic mass unit

the ________ ________ of an element is the number of protons in the nucleus of an atom of that element

atomic number

the result was a glowing beam, or _____, that traveled from the cathode to the anode.

cathode ray

the result was _________

dalton's atomic theory

_______ believed that atoms were indivisible and indestructible

democritus

atom. nothing smaller. 1st to have atomic theory. world composed of empty space and small particles. geometry drawing- black dot (atom, tiny particle)

democritus

________ are negatively charged subatomic particles

electrons

the _________ are distributed around the nucleus and occupy almost all the volume of the atom

electrons

thomson concluded that a cathode ray is a stream of ________

electrons

charge of atom based on nucleus. nucleus surrounded by electrons. predicted existence of neutron. nucleus is a heavy small heavy core of the atom. new model of atom-nuclear model (+ nucleus, - electrons) worked with becquerel drawing- (positive nucleus with electrons surrounding it)

ernest rutherford

electron cloud model electrons are probably around nucleus in this area mathematical equation to prove it drawing- electron cloud model- electrons in region around nucleus (probability of finding them here) (N in the middle with dots all around it)

erwin schrodinger

_________________ observed a cathode ray tube and found rays traveling in the direction opposite to that of the cathode rays. he concluded that they were composed of ________ ____________. such positively charged subatomic particles are called __________

eugen goldstein positive particles protons

each vertical column is a _______ or ________ they have similar _______ and ___________ properties

group family physical chemical

______________ are chemically alike because they have identical numbers of protons and electrons

isotopes

__________ are atoms that have the same number of protons but differnet numbers of neutrons. because isotopes of an element have different numbers of neutrons, they also have different ___________ ___________

isotopes mass numbers

___________________ confirmed the existence of yet another subatomic particle: the neutron.

james chadwick

found the neutron to be rays of uncharged particles proved existence of neutrons manhattan project neutrons are beams of uncharged particles (1932) drawing- protons,neutrons,and electrons; neutron model (PN in the middle with electrons surrounding it)

james chadwick

_______________ and others supposed the atom was filled with positively charged material and the electrons were evenly distributed throughout

jj thomson

found small charged particles called electrons. cathode-ray tube. drawing- plum pudding model, positive sphere, negative electrons (open circle with negatives in it)

jj thomson

in 1897, the english physicist ________ (1856-1940) discovered the electron.

jj thomson

improved on 1st atomic atomic theory . law of of partial pressures, multiple proportions, definite proportions, multiple proportions. many laws. helped with periodic table. drawing- billiard ball model (blank open circle)

john dalton

the total number of protons and neutrons in an atom is called the _______ ________

mass number

hydorgen atom is the simplest with one proton, one electron in orbital. worked with rutherford. worked on atomic bomb. bohr model of atom-planetary model drawing- planetary model. electrons move in a circular orbit around positive nucleus ( ovals crossing over each other with N in the middle and e- connected outside on the lines.)

neils bohr

______________ are subatomic particles with no charge but with a mass nearly equal to that of a proton

neutron

the _________ in an atom is the difference between the mass number and atomic number

neutrons

the _______ is the tiny central core of an atom and is composed of protons and neutrons

nucleus

each horizontal row of the periodic table is called a _______

period

within a given ________, the properties of the elements vary as you move across it from element to element

period

a _____ _____ is an arrangement of elements in which the elemtns are seperated into groups based on a set of repeating properties

periodic table

_______ and ________ have proposed many ideas on the structure of atoms

philosophers and scientists

elements are different because they contain different numbers of __________

protons

three kinds of subatomic particles are _________,____________, and __________

protons neutrons electrons

______________ directed a narrow beam of alpha particles at a very thin sheet of gold foil

rutherford

despite their small size, individual atoms are observable with instruments such as ___________________________________

scanning tunneling microscopes

__________ performed experiments that involved passing electric current through gases at low pressure

thomson

the atomic mass of an element is _______ of the atoms in a naturally occurring sample of the element

weighted

a _______ ______ ________ reflects both the mass and the relative abundance of the isotopes as they occur in nature

weighted atomic mass