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Atoms Building Blocks of Matter. Atoms Smallest particle of matter to have similar properties Atoms are particles of an element.

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Presentation on theme: "Atoms Building Blocks of Matter. Atoms Smallest particle of matter to have similar properties Atoms are particles of an element."— Presentation transcript:

1 Atoms Building Blocks of Matter

2 Atoms Smallest particle of matter to have similar properties Atoms are particles of an element

3 Subatomic Particles All atoms are made up of three primary subatomic particles: –Protons Positively-charged particle in the nucleus Has a relative mass of 1 Atomic Mass Unit (amu) –Neutrons Neutrally-charged particle in the nucleus Has a relative mass of 1 Atomic Mass Unit (amu) New theories suggest that Neutrons are slightly larger than Protons, and may be made from a Proton and an Electron that have combined

4 Subatomic Particles –Electrons Negatively-charged particle outside the nucleus Has NO relative mass –Actual mass is 1/1936 th of 1 amu –Quarks Smaller particles that make up Protons, Neutrons, and Electrons Have their own branch of Theoretical Physics

5 Properties of Atoms Atomic Number –Differentiates between elements –Equal to the number of protons Atomic Mass –Equal to the number of Nucleons (particles in the nucleus, Protons and Neutrons)

6 Properties of Atoms Normal atoms are neutral, having the same number of protons and electrons –If an atom gains electrons the atom becomes negatively charged –If an atom loses electrons the atom becomes positively charged

7 Writing Elements Write the Symbol Write the Mass Number at the upper-left of the symbol Write the Atomic Number at the lower- left of the symbol Any charge goes at the upper-right hand corner NOT ALL OF THESE ARE NECESSARY Ag

8 Counting Particles Protons = Atomic Number Neutrons = Atomic Mass – Atomic Number Electrons = Protons –ADJUST FOR CHARGE –Negative charge means MORE electrons –Positive Charge means LESS electrons Cl 35 17

9 Charge Atoms will gain, lose, or share electrons to become chemically stable “Rule of Octet” –Atoms in Groups 1 – 14 will lose electrons down to zero become positive ions –Atoms in Groups 15, 16, 17, will gain electrons up to eight become negative ions –Group 18 will not gain, lose, or share electrons Have 8 electrons anyway

10 Oxidation Number The number of electrons an atom will gain, lose, or share in order to become stable The GROUP number indicates the number of outer-shell electrons –Groups 1, 2 –Groups (except He) Always 4 or less –Go with the LOWER number of the two possibilities

11 The Periodic Table Periodic means in a regular, repeating fashion Many early designs were based on use, physical properties, and even spelling

12 Mendeleev’s Contributions Organized first working Periodic Table –according to chemical properties and atomic mass Left gaps for undiscovered elements –He was able to predict many properties of these undiscovered elements based on their location –“Ekasilicon”

13 Periodic Table Rows are called PERIODS Properties of elements repeat across a Period Columns are called GROUPS or FAMILIES Elements in a family have the same Chemical Properties

14 Group 1 Alkali Metals Highly reactive metals Have one outer shell electron

15 Group 2 Alkaline Earth Metals Reactive metals Have two outer shell electrons

16 Groups 3 – 12 Transition Metals “normal” metals Have one to ten outer shell electrons

17 Metals v. Nonmetals METALS Located to the left of the Stair-StepLocated to the left of the Stair-Step LustrousLustrous Malleable & DuctileMalleable & Ductile Good conductors of heat and electricityGood conductors of heat and electricity Solid at room temperature (except Hg)Solid at room temperature (except Hg)NONMETALS Located to the right of the Stair-StepLocated to the right of the Stair-Step Waxy or dullWaxy or dull BrittleBrittle Poor conductors of heat and electricity (good insulators)Poor conductors of heat and electricity (good insulators) Gas at room temperature (some exceptions)Gas at room temperature (some exceptions)

18 Metalloids May have properties of metals and nonmetals Located on the stair-step Some are semiconductors: they only conduct electricity under certain conditions –This makes metalloids excellent switches for computers

19 Group 17 Halogens –Means “Salt Former” Highly reactive nonmetals Have seven outer shell electrons

20 Group 18 Noble Gases Completely unreactive nonmetals –Will not bond with any atom Have a full outer shell of electrons –Eight for all but Helium –He has two outer shell electrons

21 Chemical Properties Based on the number of Valence electrons –Electrons on the outside of the atom –Called valence shell electrons, outer shell electrons Each element in a group has the same number of valence shell electrons –Groups 1, 2 is the group number –Groups 13-18, drop the “1” Helium has 2 Groups 3-12 use a different set of electronsGroups 3-12 use a different set of electrons

22 Drawing a model of an atom Draw a nucleus List the number of protons and neutrons in the nucleus Add energy levels for the number of electrons –An energy level can hold electrons equal to the number of elements in that Period –2, 8, 8, 18, 18, 32, 32

23 Differing Atoms of the Same Element IsotopesIsotopes –Atoms of an element with a different number of neutrons –Has the same chemical and physical properties as any other isotope of that element

24 Various Isotopes

25 Differing Atoms of the Same Element AllotropesAllotropes –Named when two or more natural or physical forms of an element exists Ex. for Carbon: Graphite, Diamond, BuckminsterfullerenesEx. for Carbon: Graphite, Diamond, Buckminsterfullerenes Ex. for Oxygen: O 2, O 3 - OzoneEx. for Oxygen: O 2, O 3 - Ozone

26 Allotropes of Carbon

27 Allotropes of Oxygen

28 REVIEW Atoms Elements Subatomic Particles Atomic Number Atomic Mass Charge Periodic Table Mendeleev Periods Groups Families Metals Nonmetals Drawing Atoms Isotopes Allotropes


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