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28 Cards in this Set
- Front
- Back
Atoms
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Dalton's Theory
Matter is composed of atoms Made up of subatomic particles |
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Dalton's Theory
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John Dalton
1805 Proposed that matter is composed of atoms Dalton thought atoms were solid indivisible particles We know now atoms are divisible into subatomic particles |
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Subatomic particles
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Protons
Neutrons Electrons |
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Nucleus
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Protons and Neutrons
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Protons
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Located in the nucleus(core)
Mass of 1 atomic unit Positive charge Atomic number of an element |
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Neutrons
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Located in the nucleus(core)
Mass of 1 atomic unit No charge (neutral) |
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Atomic Mass Weight
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Number of protons and neutrons
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Isotopes
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Different number of neutrons, so different atomic mass weight
Number of protons is always the same for an element Subtract an atom's atomic number from its mass to get the number of neutrons |
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Hydrogen
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pict
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Electrons
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Negative charge
1/1836th the mass of a proton - almost no mass Occupy the region outside the nucleus - called the electron cloud |
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Electron Cloud
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Size of the electron cloud determines the size of the atom
Atomic measurements are in nanometers |
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Electron Cloud
__________________ Energy Levels (Shells) |
Identified by numbers 1,2,3,4, etc or by letters K,L,M,N
The number of electrons in each shell is 2N squared First shell 2(1) =2 Second shell 2(2.2) = 8 |
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Electron Shells
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Divided into subshells s, p, d, f by line spectra characteristics
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s Subshell ("Sharp series)
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Holds 2 electrons in an atomic orbital
Orbitals can hold a maximum of 2 electrons |
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p Subshell ("principle series)
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Holds 6 electrons
3 orbitals |
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d Subshell (diffuse series)
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Holds 10 electrons
5 orbitals |
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f Subshell (fundamental series)
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Holds 14 electrons
7 orbitals |
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Electron Shells
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The number of subshells in a shell is equal to the number of the shell
Shell 1 has 1 subshell (s) Shell 2 has 2 subshells (s, p) Shells 3 has 3 subshells (s,p,d) |
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Electrons in each shell
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1 has maximum of 2 electrons
2 has maximum of 8 electrons 3 has maximum of 18 electrons 4 has maximum of 32 electrons 5 has maximum of 50 electrons |
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Filling of subshells
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After subshell 3, overlaps occur, so 4s fills before 3d; also 5s fills before 4d and 4f
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Electron Shells
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Atom is more stable if the outer electron shell is completely filled -
see pic on pg. 7 of handout |
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Electronegativity
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Positive proton in the nucleus attracts the negatively charged electrons
Electronegativity is the force between an atom's nucleus and electrons |
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Ions
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An atom's electrons stay with the atom unless a stronger force pulls them away
If you lose an electron, the atom becomes a positive ion |
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Metals
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Lose electrons
Are electron donors Become positive ions Left of periodic table Cations |
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Non-metals
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Gain electrons
Electron acceptors Become negative ions Anions |
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Polyatomic ion
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Multiple atoms that work together as a single atom and exhibit a charge
Ex: HCO (bicarbonate) |
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Polyatomic Molecules
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Have both negative and positive charges
Called Zwitterions Amino acids |
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Zwitterions
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Take or give off a H or depending on the pH
Acts as a buffer |