2. GHSGT Comprehensive Review Day 1 Structure and Properties of Atoms

3. Understanding of an Atom What is the definition of an atom?

4. 1.All matter is composed of extremely small particles called atoms 2.Atoms of a given element are identical in size, mass, and other properties; atoms of different elements differ in size, mass, & other properties ELEMENT 2 ELEMENT 2 ELEMENT 3 ELEMENT 3 ELEMENT 1 ELEMENT 1 ELEMENT 4 ELEMENT 4 Atomic Theory

5. 3.Atoms cannot be subdivided, created, or destroyed 4.atoms of different elements combine in simple whole # ratios to form chem compds 5.in chemical rxns, atoms are combined, separated, or rearranged ++ ++ Atomic Theory

6. All atoms consist of 2 regions that contain the subatomic particlesAll atoms consist of 2 regions that contain the subatomic particles –The nucleus –The electron cloud around the nucleus The nucleus is a very small region located near the center of the atomThe nucleus is a very small region located near the center of the atom –In every atom the nucleus contains At least 1 proton (p + ) which is positiveAt least 1 proton (p + ) which is positive At least 1 neutron (n o ) which is neutralAt least 1 neutron (n o ) which is neutral Atomic Structure

7. The electron cloud is the region that surrounds the nucleusThe electron cloud is the region that surrounds the nucleus –This region contains 1 or more electrons (e-), which are negatively charged subatomic particles –The volume of the electron cloud is much larger than the nucleus Atomic Structure

8. electron e-e-e-e-0 9.11x10 -28 proton p+p+p+p++11 1.67x10 -24 neutron n0n0n0n001 Structure of the Atom

9. Atomic Structure With the exception of Hydrogen, every nucleus contains 2 kinds of particles protons and neutronsWith the exception of Hydrogen, every nucleus contains 2 kinds of particles protons and neutrons –they make up the mass of the atom (Mass Number = Protons + Neutrons) Proton has a charge equal to but opposite of the charge of an elec.Proton has a charge equal to but opposite of the charge of an elec. –Atoms are neutral because they contain equal #’s of protons & electrons

10. Structure of the Atom The atoms of different elements differ in the # of protons in their nuclei and therefore in their positive chargeThe atoms of different elements differ in the # of protons in their nuclei and therefore in their positive charge –The # of protons the atom contains determines the atom’s identity Only Oxygen contains 8 protonsOnly Oxygen contains 8 protons Only Fluorine contains 9 protonsOnly Fluorine contains 9 protons Only Neon contains 10 protonsOnly Neon contains 10 protons

12. Counting Atoms Basic Truth: All atoms contain the same basic parts, but atoms of different elements have different numbers of protons.Basic Truth: All atoms contain the same basic parts, but atoms of different elements have different numbers of protons. –The PT lists atoms in consecutive order by their Atomic Number (Z) –The atomic number is directly related to the number of protons in the nucleus of each atom of that element

13. Counting Atoms The atomic number is found above the elemental symbol on the PT and it defines the type of elementThe atomic number is found above the elemental symbol on the PT and it defines the type of element –Atomic #47 can only be Ag and it also can only have 47 protons in each nucleus –Because atoms are neutral, we know from the atomic number the atom must also contain 47 electrons.

14. Counting Atoms The total number of protons & neutrons determines the mass of the atomThe total number of protons & neutrons determines the mass of the atom –Called the Mass Number –A Carbon atom, has 6 protons and 6 neutrons, so its mass number is 12 If you know the atomic number & mass number of an atom of any element, you can determine the atom’s compositionIf you know the atomic number & mass number of an atom of any element, you can determine the atom’s composition

16. ATOMS OF THE 1 ST TEN ATOMS NAME SYMBO L ATOMIC # p+p+p+p+ n0n0n0n0 MASS # e-e-e-e- HydrogenH11011 HeliumHe22242 LithiumLi33473 BerylliumBe44594 BoronB556115 CarbonC666126 NitrogenN777147 OxygenO888168 FluorineF9910199 NeonNe1010102010

17. Counting Atoms Every Cl atom has 17 protons, w/o exception, but not every Cl atom has 18 neutrons.Every Cl atom has 17 protons, w/o exception, but not every Cl atom has 18 neutrons. –Atoms with the same # of protons but contain different #s of neutrons are called isotopes. Since isotopes of an element have different #s of neutrons they have different massesSince isotopes of an element have different #s of neutrons they have different masses

18. Counting Atoms Isotopes are chemically alike because they have identical numbers of protons and electronsIsotopes are chemically alike because they have identical numbers of protons and electrons –It’s the electrons and protons that are responsible for chemical behavior Isotopes can be noted using hyphen notation (Cl-35 vs Cl-37)Isotopes can be noted using hyphen notation (Cl-35 vs Cl-37) –elemental symbol hyphen mass number

19. Isotope: one of two or more atoms having the same number of protons but different numbers of neutrons or Na-23 or Na-24

20. Practice NameSymb Atomi c # Mas s # # p + # e - # n 0 Isotopi c Symbo l Strontium W 82 70