Chapters 2-5
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element
substance that cannot be broken down to other substances by chemical reactions
compound
combination of multiple elements
elements of life
Oxygen, Carbon, Hydrogen, Nitrogen
Atoms consist of..
subatomic particles
charge of protons
positive
charge of neutrons
neutral
charge of electrons
negative
what subatomic particles are found in the nucleus
protons and neutrons
of protons =
of electrons
how do u determine # of protons?
atomic number
Atomic mass=
of protons + # of neutrons
isotope
same # of protons, different # of neutrons
radioactive isotope
unstable isotope, nucleus decays spontaneously and gives off radiation (half lives)
1st orbital can hold…
2 electrons MAX
2nd and 3rd orbital can hold…
8 electrons MAX
going away from the nucleus…
energy is absorbed
coming towards the nucleus
energy is lost
valence shell electrons
give elements their chemical properties, electron orbitals are where electrons spend 90% of their time, each shell contains a certain # of orbitals
when are atoms most stable?
when valence shells are full
how are chemical bonds formed?
filling valence shells with electrons
how do covalent bonds form?
when a pair of electrons is shared
how are polar molecules formed?
when electrons are not shared equally between atoms in a covalent bond (h2o)
ionic bonds
attraction between 2 oppositely charged ions
how do chemical reactions occur
making or breaking of chemical bonds, atoms are not made or lost they are rearranged