unit1 section1 atomic structur chem
where is the mass in an atom most concentrated
nucleus
what can you find in the nucleus
protons and neutrons
what is the relative mass and relative charge of a proton
relative mass: 1, relative charge: +1
relative mass and charge of neutron
mass: 1, charge: 0
relative mass and charge of electron
mass: 1/2000, charge: -1
what is mass number
tells you the total number of protons and neutrons in the nucleus
what is atomci number
number of protons in an nucleus which helps identify the element it is. all atoms of the same element have the same number of protons
what do neutral atoms have the same number of
electrons and protons
do negative ions have more electrons or protons
they have more electrons than protons
do postive ions have more electrons or protons
they have more protons than electrons
relative atomic mass defenition
the ratio of the average mass of one atom of an element to one twelfth of the mass of an atom of carbon-12
isotope definition
elements that have the same number of protons but diff number or neutrons
do isotopes have the same chemical properties
yes, since the electron config decides the chem properties and isotopes have the same electron config
do isotopes have the same physical properties
no, they have diff phys properties because the mass of the atom is diff eg diff densities or rates of diffusion
what did john dalton do
19th century he described atoms as solid spheres and said that diff spheres make up diff elements
what did jj thomson do
in 1897, he discovered the plum pudding model which is when it was a solid postive charged sphere with negative electrons embedded in it
what did ernest rutherford do
gold foil experiment: fired positive charged alpha particles at gold foil, most went straight through but some deflected back. proved plum pudding model wrong. rutherford made nuclear model
why was rutherfords idea of the atom wrong
because the cloud of electrons idea would suggest that it would quicky spiral down into the nucleus making it collaspe. so neils bohr came up withe idea that electrons are in fixed orbitals.
what happens when electrons move between shells
electromagnetic radiation is emitted or absorbed
why was bohrs model proven wrong
because not all electrons in a shell have the same energy. instead they made subshells
relative isotopic mass
is the mass of an atom of an isotope of an element on a scale where an atom of carbon 12 is 12