Everything Flashcards
John Dalton
all elements are made up of small particles called atoms. they cannot be created or destroyed. atoms of different elements have different properites
J.J Thompson
Discovered the electron. proposed the plum pudding model: negative electrons embedded into a sphere of positive charge
Ernest Rutherford
he proved that atoms consisted of electrons reveolving around positive particle protons
James Chadwick
he showed the nucleus of atoms continued 2 different types of particles. neutral particles are called a neutron. they were difficult to detect because they had not charge
atomic number
the number of protons in an atom
mass number
total number of proton and neutrons in an atom
why is an atom neutral
the protons cancel out the electrons
group number
number of electrons in the outer shell
period number
number of shells
what are isotopes
an element with the same atomic number but different mass number
formation of ions
noble gases all have a full outer shell of electrons . this makes the noble gases unreactive. all the other electrons want to achieve the stability of a noble gas in a chemical reaction
ions are what
charged particle that can lose or gain electrons
metals what
lose electrons to form positive ions: cations
non metals what
gain electrons to form negative ions: anions
chemical bonds
if an atom does not have a full outer shell it will react with another atom to achieve a full outer shell
