2 The Atoms FamilyAtom: the smallest part of an element. Name means “indivisible”
3 Who’s atom is it? Dalton (bb) Rutherford Electron cloud model Thompson (Plum Pudding)Bohr(planetary)Standard Model
4 Parts of an AtomNucleus:The main center of an atom. Made up of protons and neutronsProton:In the nucleus. Has a + charge. Atomic number tells the number of protonsNeutron:In the nucleus. Has NO charge. Is there to keep protons apart
5 Parts of an ATOMElectrons: In the electron cloud, has a negative charge.
6 The Same, But DifferentIsotopes:An element with different numbers of neutrons.Atomic mass - atomic number = number of neutrons.Example: Hydrogen (mass) - 1 (atomic #) = neutronsHaving an unequal number of neutrons and protons can make an atom unstable!
7 B. Subatomic Particles Most of the atom’s mass. Atomic Number NUCLEUSELECTRONSPROTONSNEUTRONSNEGATIVE CHARGEPOSITIVE CHARGENEUTRAL CHARGEMost of the atom’s mass.Atomic Numberequals the # of...
8 Let’s reviewName the two sub-atomic particles found in the nucleus of an atom:Proton and NeutronWhat is the charge of a proton?PositiveWhat is the charge of a neutron?No charge (neutral)Where are the electrons at?Orbiting the nucleus
9 II. Electron Cloud Model Orbital Energy Levels Bohr Model Diagrams Atomic StructureII. Electron Cloud ModelOrbitalEnergy LevelsBohr Model Diagrams
10 Niels Bohr (1913) Bright-Line Spectrum tried to explain presence of specific colors in hydrogen’s spectrumEnergy Levelselectrons can only exist in specific energy statesPlanetary ModelNiels Bohr (1913)
12 Niels Bohr (1913) Planetary Model: Bright-line spectrumPlanetary Model:electrons move in circular orbits within specific energy levels
13 electron shellsElectrons different amounts of energy and at different energy levels or electron shells.Electron shells (levels) determine… how an atom behaves when it encounters other atoms
14 Levels1st Level: closest to nucleus. Has 1 orbital. Can hold 2 electrons2nd level: next one out. Has 2 orbitals. Can hold 8 electrons.3rd level: Holds 8 electrons.4th level: Holds 18 electrons
15 Why are electrons important? Elements have different electron configurations so different levels of bondingValence electrons are the electrons in the outer most shell.Valence electrons are important because they affect how the element reacts with other elements.
16 How many valence electrons are in these different atoms?
17 Octet Rule = atoms tend to gain, lose or share electrons so as to have 8 electrons C would like toN would like toO would like toGain 4 electronsGain 3 electronsGain 2 electrons
18 Ne C. Stability Octet Rule most atoms form bonds in order to have 8 valence e-full outer energy levellike the Noble Gases!NeStability is the driving force behind bond formation!
19 Electron Dot Structures Symbols of atoms with dots to represent the valence-shell electronsH He: Li Be B C N O : F :Ne : Na Mg Al Si P S :Cl :Ar :
20 Learning Check A. X would be the electron dot formula for A. X would be the electron dot formula for1) Na 2) K 3) Al B X would be the electron dot formula1) B 2) N 3) P
21 Stability Why is it important for an atom to be “stable”? So it is less reactive.Why are noble gases stable?They have a full energy level.