Elements and the periodic table Flashcards
Matter
Anything that occupies space and has a mass
Solids
Fixed 3D lattice
Attraction between particles very strong- high MP and BP
Only vibrate- don’t move out of fixed positions
Liquids
Particles disordered- collide into each other and walls of the container
volume remains constant
attraction between particles weaker than in solid state
Gases
Particles far apart and disordered
Collide into each other and move until they collide with the walls of the container
volume is not constant
Attraction between particles weakest
Mass
Measure of the quantity of matter in an object, regardless of the gravity force
Weight
Force that gravity exerts on an object
Substance
Form of matter with constant composition, distinct properties and can write a chemical formula
Mixture
combination of two or more substances
no constant composition
cannot write a chemical formula
Element
Substance made of only one type of atom
Compound
Substance made of two or more different types of atoms
Chemical identity of an atom
Determined solely by its atomic number
Isotopes
Atoms that have the same atomic number but different mass numbers
Protons an electrons determine chemical properties of an element
Neutrons dont take part in chemical reactions
Isotope similarities
Atomic number
Chemical properties
Number of electrons
Isotope differences
Mass number
Number of neutrons
Stability of nucleus
MP and BP table
Solid Liquid Gas
MP + - -
BP + + -
Hydrogen spectra
Neils Bohr’s shell model
Visible hydrogen spectrum consists of four lines (red, green, blue and violet) observed by passing an electric current through hydrogen gas
electrons move around nucleus at specific energy levels
can transition from a lower energy level to a higher energy level by absorbing energy
higher energy electron- excited state
excited electron is unstable and falls back to ground state, emitting the absorbed energy
This energy corresponds to the coloured lines on the spectrum
electron in lowest possible energy shell- ground state
Schrodinger
Quantum mechanical model
electrons form a cloud of negative charge around the nucleus
shells, sub shells, orbitals
Valence electrons
involved in chemical reactions because they are unstable
Octet rule
Outermost shell can never contain more than 8 electrons regardless of the maximum possible number for that shell