Chemistry Chapter 3 Flashcards
number of protons in the atom
identifies the element
atomic number
1=1.660 x^-27 kg
mass of proton and neutron =1
mass of electron= 0.0005
atomic mass unit AMU
number of protons and neutrons
mass number
atoms of the same element with a different atomic mass because of a different number of neutrons
isotopes
isotopic notation of a nuclide
4 superscript- mass # protons + neutrons
2 subscript - protons
next to He
mass number on periodic table is the ________________________- of the naturally occurring isotopes of an element
average atomic mass
how do you calculate the average atomic mass
multiply the atomic mass of each isotope by the % in decimal form-> add the results together
an atom is defined as the smallest part of an element that….
retains the chemical identity of that element
the fact that carbon dioxide always contains 73 percent oxygen by mass is an illustration of
the law of constant composition/definite proportion
a cathode ray consists of
electrons
the electron was discovered by
thomson
the scientist who measure the charge of the electron was
millikan
the experiment that revealed the charge of the electron involved the use of
oil droplets
rutherford called the core of the atom the
nucleus
what makes up an atom (3)
electron
proton
neutron
what is found on the outside of the nucleus of the atom
electron
what is the approximate atomic mass of an neutron, in amu
1
what is the approximate atomic mass of an electron in amu
essentially 0
the atomic number of an atom is defined as its
number of protons
the mass number of an atom is defined as its
total number of neutrons and protons
an element’s identity is based on its
atomic number
two atoms are isotopes if they contain
the same number of protons but different numbers of neutrons
the symbol indicates a fluorine atom that contains
19 F
9
9 protons and 10 neutrons
what did Democritus contribute to the understanding of matter
came up with the idea of the atom
why were Democritus’s ideas not accepted at the time
people believed Aristotle instead that everything is made up of earth water wind fire
Why was Democritus’s ideas reconsidered in the eighteenth century
experimental data, proved particles are made of different things
Greek philosopher
idea of atom=indivisible, which was the foundation of the atomic theory
Democritus
in a chemical reaction matter cannot be created or destroyed, it can only change form
law of conservation of mass
a chemical compound contains the same elements in exactly the same proportion by mass regardless of the sample or source of the coumpound
law of definite proportion
if two or more different compounds are composed of the same elements then the ratio of the masses of the elements is always a ratio of small whole numbers
law of multiple proportion
part of _______- atomic theory
- all matter is composed of ___________
- atoms of a given element are _________ in size, mass, and other properties; atoms of different elements __ in size, mass, and other properties
- Atoms can’t be ___ created or destroyed
- Atoms of different elements combine in simple __________ to form _________
- in ________ atoms are combined, separated or rearrganged
Dalton’s
- extremely small particles called atoms
- identical, differ
- subdivided
- whole number rations, chemical compounds
- chemical reactions
Modern atomic theory
based on Dalton but modified
All matter is composed of _____
atoms of any one element _______ from atoms of another element
atoms
differ in properties
smallest part of an element that retains the properties of that element
atoms
atoms contain
subatomic particles
protons
neutrons
electrons
electrons possess energy; travel in a straight line; cannot penetrate metal
crooke’s tube/ cathode ray tube
used a magnetic field around the cathode tube
showed; electron affected by magnet
concluded; all atoms contain e-; e- are negative: assumes positive matter must exist
J.J Thomson
oil drop experiment
determined the charge ( negative) on the e-
calculated the mass of e-
mass= 9.109x10^-31 kg
millikan
Gold foil experiment
showed nucleus is dense and positive: volume of nucleus very small compared to size of atom; e- actually occupy very little space but effectively occupy all the space outside the nucluse
rutherford
proton has a charge= to the charge of the e- but opposite
proton=+1; e-=-1
composition of the nucleus
positive charge mass=1.67x10^-27kg
proton
neutral charge; mass=1.675x10^27kg
neutron
protons should repel each other but when very close actually have a strong attraction;
same attraction with neutron
neutron forces, proton-neutron forces
nuclear binding force (strong force)
forces in the nucleus
