2What is an atom?An atom is the smallest particle of an element that retains its identity in a chemical reaction.Word origin: atom comes from the Greek word atomos meaning “ indivisible”
3Elements & CompoundsWhat would atoms of an element, mixture and compound look like at a microscopic level?
4Subatomic Particles The parts that make up an atom! protons neutrons electronselectronprotonnucleusneutron
5Subatomic Particles Electrons Protons Neutrons Found in the nucleus Identifies the element#of protons = specific elementResponsible for chemical and physical propertiesSpin around in set regions outside of nucleusMost important in chemical reactionsFarthest electron away from nucleus determines how atoms chemical to combine to one another.Found in the nucleusPlays no role in chemical behaviorPurpose: to put space between protons
6Subatomic Particles How big is an atom? NameSymbolChargeRelative MassProtonp++11NeutronnoElectrone--10 (1/1840)How big is an atom?Imagine the nucleus is the size of a marblelocated in the middle of the football field,the electron would be in the classroom the size of a period!
8Periodic Table Categories: Rows: periods Columns: groups or families MetalsNonmetalsMetalloids(B, Si, Ge, As, Sb, Te, At)Rows: periods7 periodsColumns: groups or families18 Groups1A: Alkali Metals2A: Alkaline Earth Metals7A: Halogens8A: Noble gasesB Groups: Transition and Inner Transition Metals
9Si Periodic Table 14 Silicon 28.086 Atomic Number Symbol Element name Atomic Mass
10Si Important Numbers Atomic Number 14 Silicon has 14 protons Counts the number of protons in an atom within the nucleusAtomic Number= # of protons14SiSilicon has 14 protons
11Atomic Number A. Nitrogen B. Potassium C. Neon State the number of protons for atoms of each of the following:A. NitrogenB. PotassiumC. Neon
12Atomic Number A. Nitrogen B. Potassium C. Neon 7 protons 19 protons State the number of protons for atoms of each of the following:A. Nitrogen7 protonsB. Potassium19 protonsC. Neon10 protons
13Number of Electrons An atom is neutral The net charge is zero Number of protons = Number of electronsAtomic number = Number of electronsRemember: proton = +1 electron = -1
14Number of Electrons14Si14 electrons14 protons-14+14= 0 neutral
15Si Important Numbers Mass Number 14 Atomic Mass Silicon 28.086 Counts the number of protons and neutrons in an atomORDetermined by: the whole number closest to the Atomic Mass
16Si 28 14 Mass Number silicon-28 Show the mass number and atomic number Atomic SymbolsShow the mass number and atomic numberGive the symbol of the elementMass Number2814Sisilicon-28Atomic Number
17Determine the Mass Numbers 4Be9.012227Co58.93310Ne20.17995920
18Write the Symbol and Name for each 4Be9.012227Co58.93310Ne20.179Be945927Co2010Neberyllium-9cobalt-59neon-20
19Mass Number O P Zn The total number of particles in the nucleus # of protons + # of neutronsTo determine the number of neutronsMass number – Atomic number = # of neutronsO16831156530#p#n#ePZn8p+30p+15p+8no35no16no8e-30e-15e-
20IsotopesThe atomic number identifies the element, but an element may have atoms with several different mass numbers.Most elements consist of several different isotopesSame number of protons , Different number of neutrons3517Cl3717Clchlorine-35chlorine-37
21Isotopes of HydrogenNaturally occurring hydrogen consists of 3 isotopes, protium (H-1), deuterium (H-2), and tritium (H-3). State the number of protons, neutrons, and electrons.123#p#n#eHHH11112111
22An atom of Calcium (Ca-40) A. Number of protonsB. number of neutronsC. What is the mass number of a calcium isotope with 19 neutrons?
23Atomic Mass This is NOT a whole number A given element can have atoms with several different mass numbers.Average mass of the atoms with all possible mass numbersWe will calculate later
24Write the atomic symbol A. 11p+, 12no, 11e-B. 17p+, 20no, 17e-C. 47p+, 60no, 47e-
25Write the atomic symbol 2311NaA. 11p+, 12no, 11e-B. 17p+, 20no, 17e-C. 47p+, 60no, 47e-3717Cl10747Ag
26Ions Na1+ Cl1- Atoms with a charge (positive or negative) Remember atoms are neutral, therefore if an atom has a charge we call it an ion.Ions- Atoms which gain or lose an electronatom ion#p 11 11#e 11 10#p 17 17#e 17 18Why do the electrons change?Na1+Cl1-
27Why? If protons change…new______?________ If neutrons change…new______?______If electrons change….new _____?______
28Why?If protons change…new elementIf neutrons change…new isotopeIf electrons change….new ion
33Atomic MassComing back to this…Atomic mass is the weighted average mass of all the atomic masses of the isotopes of that atom.So we involved all the different forms of ATOMS of an element (ions not an issue here) and how frequent they are
34Average Atomic Mass cont. To find the Average Atomic Mass (generally referred to as the atomic mass of an element) we need to use two thingsThe mass of the isotopeMultiplied by its frequencyThen we add all the forms up.
35Example of Average Atomic Mass Cl-35 is about 75.5 % and Cl-37 about 24.5% of natural chlorine.35 x =10035.537 x =Add Us Up
36Rubidium has two common isotopes, Rb-85 and Rb-87 Rubidium has two common isotopes, Rb-85 and Rb-87. If the abundance of Rb-85 is 72.2% and the abundance of Rb-87 is 27.8%, what is the average atomic mass or rubidium?