Presentation on theme: "The Atom What to look for: Three Essential Questions"— Presentation transcript:
1The Atom What to look for: Three Essential Questions E. Q. #1 = What are the parts of an atom?E. Q. #2 = In what manner can subatomic particles be differentiated?E. Q. #3 = How does the atomic structure impact chemical change & reactivity?
2The Building Block of Matter 400 BC Democritus (Greek Philosopher)Atomos = “indivisible”…like a brick is used to build a building; an atom is used to build all matter…
3First Atomic Theory 1808 John Dalton (English Chemist) Using experiments formulates the first atomic theoryAll elements are composed of indivisible particles called atomsAtoms of the same elements are exactly the sameAtoms of different elements are differentTwo or more elements combine to form compounds
4Subatomic ParticlesThe idea that the atoms was not a solid sphere, but a composition of small particles which came to be known as subatomic particlesJulius Plucker, William Crooks & J J Thomsonmid-1800’s
8The atom is mostly empty space Most of the particles passed straight through to gold foil.First important discovery by Rutherford
9The NUCLEUS is Discovered 1911 Rutherford proves that the particles that do not pass through are hitting a small, dense center of the atom called the nucleus.Rutherford later goes on to discover the proton
103Name three major discoveries made by Ernest Rutherford & the Gold Foil Experiment:1. _______________________________________2. _______________________________________3. _______________________________________What are the two results of firing particles at atoms in the foil of the Gold Foil Experiments:1. _______________________________________2. _______________________________________21Who was the first to attempt to form a complete atomic theory?1. _______________________________________
11Electron Energy Levels 1913 Niels Bohr (Danish physicist) discovers the electrons travel around the outside of the atom on different energy levelsThe Bohr Model = “solar system” model
12The Neutron is Found1932 James Chadwick proves the existence of the neutron.Only 4 years later the neutron is used to split the first atomWhy was the neutron’s existence more difficult to prove?What evidence hinted of its existence? “the missing mass”E. Q. #1 = What are the parts of an atom?
13The Subatomic Particles LocationMass (AMU)ChargeElectronElectron CloudnegativeProtonNucleus1positiveNeutronneutralE. Q. #2 = In what manner can subatomic particles be differentiated?
14Finding the Number of Subatomic Particles in an Atom Atomic Number = the number of protons in the nucleus of an atomIdentifies each elementHydrogen is 1 and it has 1 proton in its nucleus (only hydrogen has 1 proton)Helium is 2 and it has 2 protons in its nucleus (only helium has 2 protons)
15ElectronsIF the atom is neutral (same number positive charges as negative charges) then the number of electrons will be the same as protons.ION = a charged atom (unequal number of protons and electrons)+1 charge = the atom LOST one electron-1 charge = the atom GAINED one electron+2 charge = LOST 2 electrons-2 charge = GAINED 2 electrons and so on
16Example of Ions Sodium will lose one electron when it bonds Na+1 or Na+Sodium’s atomic number is 11, so it has 11 protons.The +1 charge means Na+1 has 10 electrons
17Another Example Chlorine will gain an electron when it bonds Cl-1 or Cl-Chlorine’s atomic number is 17, so it has 17 protonsThe -1 charge means Cl-1 has 18 electrons
18Mass # - Atomic # = # of neutrons Mass NumberThe two subatomic particles that have mass?Proton and neutron, both found in the nucleusMass Number = # of Protons + # of NeutronsMass # - Atomic # = # of neutrons
19Practice Problems Mg 12 24 K 19 39 20 Na+1 11 23 +1 10 F-1 9 -1 Mg+2 SymbolAtomicNumberMassChargeProtonsNeutronsElectronsMg1224K193920Na+11123+110F-19-1Mg+2+2Do Parts of the Atom & Atomic Structure practice sheet now.
20ISOTOPESAtoms of the same element with a different number of neutrons.Ex: carbon-12 & carbon-14Carbon-126 protons6 neutrons6 electronsCarbon-148 neutrons
22The ELECTRON CLOUDThe electron cloud is separated by different energy levels.Electrons with less energy travel on the levels closest to the nucleus.Energy levels are divided into sub-levelsSub-levels are divided into orbitalsAll of these levels, sub-levels & orbitals can overlap.
23VALENCE ELECTRONS Valence electrons = the outermost electrons The electrons involved in bondingDetermines the chemical properties of an atomE. Q. #3 = How does the atomic structure impact chemical change & reactivity?Do Practice sheets What Is This Atom Now? 1 & 2 now.
24Maximum # of electrons on each energy level More about ElectronsMaximum # of electrons on each energy levelLevel 1 = 2 electronsLevel 2 = 8 electronsLevel 3 = 18 electronsLevel 4 = 32 electrons
25“the Stable 8” gain electrons lose electrons share electrons Due to the overlapping levels, sub-levels and orbitals the maximum number of outer most electrons is EIGHT.An atom is becomes stable when it outer-most energy levels is full of electronsThis explains the chemical bonding properties of the atomsAtoms will do one of three things in order to fill their outer most energy levels.gain electronslose electronsshare electrons
26Concepts Coming Up Next The number of valence electrons an atom has determines the group it becomes to on the PERIODIC TABLE.Groups or families of elements on the periodic table has similar chemical properties.
27Concepts Coming Up Next Valence electrons determine how atoms will bond with other atoms in order to complete their outer-most energy level.The Stable 8CHEMICAL BONDINGIonic bonding (gaining/losing of electrons)Covalent bonding (sharing of electrons)