C1.2 Atomic structure Flashcards
what is an atom?
the smallest particle of an element that still has its chemical properties - diff elements made from diff atoms
what is a molecule?
made from 2 or more atoms joined together - joined by chemical bonds
radius of an atom
approx 10^-10m
what subatomic particles is the nucleus of an atom made from?
protons and neutrons
proton - relative mass, relative charge
1, +1
neutron - relative mass, relative charge
1, 0
electron - relative mass, relative charge
0.0005, -1
what is the atomic number?
the number of protons in its nucleus
what is mass number?
the total number of protons and neutrons
what is an isotope?
atoms (of the same element) with same number of protons and electrons but diff numbers of neutrons. TMT same atomic number but diff mass number. Have identical chemical properties but diff physical properties
what is an ion?
a charged particle
how are ions formed?
when atoms, or groups of atoms, lose or gain electrons - e.g. during a chemical reaction
what did John Dalton suggest?
that all matter is made from atoms, diff elements have diff atoms, all atoms of an element are identical
what did John Dalton believe an atom looked like?
a tiny solid ball - technology of his time didn’t let him investigate in enough detail
what id J.J. Thompson discover?
the electron
observation of J.J. Thompsons plum pudding model
- atoms contain electrons
- atoms are neutral overall
- atoms are spheres of + charge with electrons dotted around inside
what did Ernest Rutherford do?
pointed beams of positively charged particles, called alpha particles at thin gold foil - some particles went straight through, some slightly changed direction, some bounced back.
what did Ernest Rutherford suggest?
an atom has a positively charged nucleus, containing most of its mass and outside the nucleus, electrons orbit like planets in a solar system
what did Neils Bohr do?
realised orbiting electrons would be attracted to positive nucleus and would rapidly spiral inwards. Bohr showed electrons occupy fixed energy levels, or shells, around the nucleus
what are molecules?
made up of 2 or more atoms
