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Intro to Chemistry. Atomic Structure. Nucleus- center of an atom -contains protons (which are positive) -contains neutrons (which are neutral). Ex- Sodium:. Bohr Model of Atom. Atomic Structure. Outside the Nucleus:
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Atomic Structure • Nucleus- center of an atom -contains protons (which are positive) -contains neutrons (which are neutral) Ex- Sodium:
Atomic Structure Outside the Nucleus: • Electrons (which are negative) surround the nucleus in energy levels 1st energy level = holds 2e 2nd energy level = holds 8e 3rd energy level = SAVE 4th energy level = FOR CHEMISTRY!!
Subatomic Particle Organized Atomic Mass
Chemistry tidbits • Chemical Symbol- letter representing the atom (sometimes from Latin)
Chemistry tidbits • Atomic number = number of protons • Mass number = # protons + # neutrons • Don’t bother to weigh the air inside the box • So how can you calculate NEUTRONS??
Calculating Neutrons is a simple algebraic problem… • Mass Number = protons + neutrons • Atomic Number = protons • Write the equation… • Mass Number= Atomic Number + neutrons • #Neutrons = (mass number – atomic number)
Chemistry tidbits • Usually can assume: • # protons = # electrons • ONLY true for NEUTRAL ATOMS!
And remember… • Don’t mess with the • PROTONS!!!
So what CAN we “mess with?” • Neutrons… • Changes the MASS • Get an ISOTOPE • Electrons… • Changes the CHARGE • Get an ION
Atomic Mass Mystery… • Look at the atomic mass for Oxygen. What does it say (exactly?) • 15.9999 • What is the atomic mass? • P + N • So what the heck!?!?! • Average of the actual isotopes on Earth!!!
Isotopes • Isotopes are different atoms of the same element that contain the same number of protons but different number of neutrons. • Examples • Cl-35 vs. Cl-37 17P 17P 18N 20N
How to write isotopes… • Mass/Hyphen Notation: • Especially important for a form of the isotope that is NOT the “usual” • Write the symbol, a dash, and the mass # for that isotope • Ex’s • C-14 • C-12
How to write isotopes… • Nuclear Symbol Notation • Includes the symbol, atomic #, and the mass # for that isotope • Ex’s 14 6 C
What else CAN we “mess with?” • Neutrons… • Get an ISOTOPE • Electrons… • Get an ION
Periodic Table tidbits • Period table organization – organized by increasing atomic number • Split into metals (left side of stair step line) and nonmetals (right side of stair step line) • Metalloids- surround the stairstep line • Groups (families) – vertical columns (#1-18) • Periods – horizontal rows (#1-7)
Periodic Table tidbits • Period table organization – organized by increasing atomic number • Split into metals (left side of stair step line) and nonmetals (right side of stair step line) • ONE EXCEPTION • Hydrogen! • vertical columns (#1-18) • Groups • horizontal rows (#1-7) • Periods
Metals-left side of table • Exist as solids at room temperature • Shiny • Good conductors of heat & electricity • Malleable (can be bent)
Nonmetals-right side of table • Most are gases at room temperature • Some are brittle solids- carbon, sulfur, iodine, & phosphorus • Most donot conduct heat & electricity well
Metalloids- next to zigzag line b/w metals & nonmetals • Properties fall between neighbors on both sides • Most are silvery in appearance, brittle, poor conductors of heat & electricty
Transition Metals • Metals- which are less reactive than the alkali or alkaline earth metals • Often exist as oxide or sulfide ores ex. Iron sulfide or iron oxide • You’ll learn more in chemistry about these elements
Major Groups on periodic table • Alkali metals- group 1- most reactive • Alkaline earth metals- group 2 • Transition metals- groups 3-12 • Metalloids- surround stairstep line • Halogens- group 17 • Noble gases-group 18 (inert gases-stable; nonreactive) • Periodic table
Lewis Dot Structures • Lewis dot diagrams- display the number of valence electrons (outermost electrons) around the element symbol • Used to show how atoms of different elements bond and form compounds • Hint- use group number to find valence electrons
