Ch 4 K Introduction to Atoms

Ch 11 Introduction to Atoms1The Beginning of Atomic TheoryDemocritus & AristotleCan you cut a piece of paper in half and cut those halves in half and continue until you are left with 1 particle?If you could do this you would end up with what Democritus called an _________= ______________________

Aristotle _____________ with democrituss idea. He believed that ___________________________________

Who was correct? Aristotle or Democritus??

2The Beginning of Atomic Theory____________________was correct!

Matter is made of particles which we call ___________.Atom -

3The Beginning of Atomic TheoryDalton 1803Daltons atomic theory was based on _________________!All substances are made of ______Atoms are small particles that cannot be _____, _______, or _________.Atoms of the same element are _________ and atoms of different elements are _________.Atoms join with other atoms to make _____ substances.

4The Beginning of Atomic TheoryNew information didnt quite fit with _______ ideas. His atomic theory had to be _________.

Thomson- 1897Discovered the ____________ charged particlesThere are __________ inside the atom. Atoms can be broken down further. (Dalton thought atoms were solid spheres so hes wrong)

5CATHODE-RAY TUBEA positively charged plate was attracted to a ______.Therefore, the beam must be made up of ________ charges.Thomson concluded these negative charges are _______ in every kind of _______.

6The Beginning of Atomic Theory________- A subatomic particle that has a negative charge.Thomson described his model of the atom like plum pudding. Today you might call it the ______________ _____ model. (with electrons represented by _________________.)

7The Beginning of Atomic TheoryRutherford- 1909Rutherford was a _____________ of Thomsons. He tried to help prove Thomson theory was _______ and ended up proving him ______! He aimed a beam of small, _________________ ( particles) at a thin piece of gold foil.Photo paper behind the gold recorded where the charged particles hit.Surprising ResultsHe thought the particles would _______________ the gold in a straight line.Some particles were ________. Some shot right ______. 8Rutherfords Gold-Foil ExperimentRutherford determined an atom must be mostly ______ ______ with a tiny part made of highly dense material.

9Rutherfords Model________ The centrally located, tiny, extremely dense positively charged part of an atom.

10The Beginning of Atomic TheoryBohr 1913Niels Bohr proposed that electrons move around the nucleus in _______________________________.Electrons can jump from path to path but cannot exist in _____________ paths.Think of ________ on a ladder. You can stand on the rungs, but not ________ the rungs.Or think of planets in our solar system they do not stray off the set path or ___________.

11The Modern Atomic TheorySchrdinger and HeisenbergElectrons ________ travel in definite paths as Bohr suggested.The exact path of the electron ______ be predicted.There are regions where it is likely to be found called ______ __________.

124.2 The AtomHow small is an _____?A penny contains __________ atoms. (20,000,000,000,000,000,000,000 atoms)An atom is made up of _______, _______, and _________.

The NucleusProtons The mass of protons are measured in atomic mass units (amu). Each proton has a mass of __________ _________- Particles in the nucleus that have ___ electrical charge.Neutrons have a mass of 1 amu. (Same as _________)

13The AtomOutside the nucleus_________ are found outside the nucleus. They have a _______ charge. They have a mass of almost _____.

If the number of protons __________ the number of electrons, the atom is ______________

14HOW DO ATOMS OF DIFFERENT ELEMENTS DIFFER?Atoms of different elements have different numbers of ____________.No two elements have the same _____________.Atomic number is the number of ________ in an atom. All atoms of the _____________ have the _________ atomic number.

15HOW DO ATOMS OF DIFFERENT ELEMENTS DIFFER?So how do we figure out the number of neutrons for an atom?The number of _____________ = the number of _______________

Mass number The mass number does not include the mass of ____________ because they are so ___________and have very little effect.

HOW DO ATOMS OF DIFFERENT ELEMENTS DIFFER?Where do you find these numbers? On the ____________________ !

C C C # of neutrons = _________ - _________# of neutrons in C = ____ - ____C P+ = No=E- =

____________# __ + # __ # ________HOW DO ATOMS OF DIFFERENT ELEMENTS DIFFER?Mass #Atomic #ProtonsNeutronsElectronsLiBeBCNOFNakDRAWING BOHR MODELS OF ATOMSDraw the nucleus and label with #p & #nDraw electron orbitals1st orbital can have ______ electrons only2nd and 3rd ring can each have ______electronsFill _____________________Inner rings must be filled first before any electron enters a higher ring!!!!!Examples:

Changing AtomsIf you change a persons hair color does it change who they are? Weight?What subatomic particle determines an atoms identity?___________ Therefore, the number of electrons and neutrons can change in the atom and it is still the same atom.

If the number of protons __________ the number of electrons, the atom is ______________If the number of protons ___________ the number of electrons, the atom becomes charged and we call it an _______.Positively charged ions Negatively charged ions -

ISOTOPES_________- Atoms that have the same number of protons, but have different numbers of neutrons.Examples: Hydrogen -1 and Hydrogen -2Naming IsotopesWrite the __________ of the element, followed by a hyphened and the _____________________ of the isotope.Ex. A hydrogen atom with 1 proton and 0 neutronsA hydrogen atom with 1 proton and 1 neutron

21ISOTOPESMass Number The sum of the _________________ in an atom. (__________ are not included.)Mass # = protons + neutrons

Atomic Mass The _____________ of the masses of all the ___________ occurring isotopes of that element.

22Solving the Atomic MassEx: Skittles consist of Orange 1 which is 25% of the Skittles and Red 2 which is 75% of skittles.

Step1: change percents to decimals.

Step 2: multiply the decimal by the mass

Step 3: add the two answers together

Solving for Atomic MassEx: Chlorine-35 which is 76% of the Chlorine atoms and Chlorine-37 which is 24% of Chlorine atoms.

Step1: change percents to decimals.

Step 2: multiply the decimal by the mass

Step 3: add the two answers together24