2.1.1: Atomic structure and isotopes Flashcards
What is the relative mass of an electron ?
1/2000
Give the order of people in the history of the atom
- Dalton
- Thompson
- Rutherford
- Bohr
- Chadwick
What did Dalton discover ?
Atoms are indivisible spheres. Each element is made from different spheres containing only 1 type of atom
What did Thompson discover ?
ELECTRON .Plum pudding model suggested negative charges randomly distributed in a sea of positive charge
What did Rutherford discover ?
PROTON+NUCLEUS. Alpha particle scattering experiment proved that atoms were mainly empty space as most particles passed through, nucleus was positively charges and mass is concentrated in nucleus as some particles were reflected back
What did Bohr discover ?
Atomic model - electrons orbit nucleus at specific energy levels/shells
What proof supported Bohr ?
When EM radiation is absorbed electrons move between shells and move down when radiation is emitted
Why did Bohr want to disprove Rutherford’s theory ?
Didn’t believe clouds of electrons could collapse into positive nuclei
What did Chadwick discover ?
NEUTRON
What is the current understanding of the atom which disproves previous theories ?
Electrons don’t have the same energy in shells , instead there are sub shells which explain ionization trends
Explain the chemical and physical properties of isotopes
- Chemical properties are identical as same electronic configuration
- Physical properties ( density ) can differ
What is Mr used for ?
Covalent compounds / simple molecules
What is relative formula mass used for ?
Ionic compounds / giant structures
Define relative atomic mass (Ar)
The weighted mean mass of an atom of an element compared with one twelfth of a mass of an atom of carbon-12
Define ion
An atom or molecule that is charged due to the loss or gain of one or more electrons
