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Ch 3 Atoms and Periodic Table Notes


Ch 3 Atoms and Periodic Table Notes Vocab: nucleus, proton, neutron, electron, Energy level, orbital, Valence electron, Periodic law, Period, Group, Ionization, Ion ... – PowerPoint PPT presentation

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Title: Ch 3 Atoms and Periodic Table Notes

Ch 3 Atoms and Periodic Table Notes
  • Vocab nucleus, proton, neutron, electron, Energy
    level, orbital, Valence electron, Periodic law,
    Period, Group, Ionization, Ion, Cation, Anion,
    Atomic number, Atomic mass number, Isotopes,
    Atomic mass unit, Average atomic mass, Metals,
    Nonmetals, Semiconductors, Alkali metals,
    Alkaline-earth metals, Transition metals,
    Halogens, Noble gases

3.1 Atomic Structure
  • What gives different matter distinct properties?
  • - the atoms in that type of matter
  • Atoms are tiny units that determine properties of
  • - each element has its own atom

Daltons Atomic Theory 1808 English
  • Every element is made of tiny particles called
    atoms that cant be divided.
  • Atoms of the same element are exactly alike.
  • Atoms of different elements can join to form
  • - We have since learned that atoms can be divided.

Atomic Structure
  • Nucleus center of atom
  • Protons neutrons
  • Overall positive charge

  • Electron Cloud surrounds nucleus
  • Contains space where electrons are found
  • Overall negative charge
  • Overall positive and negative attraction keeps
    electron cloud close to the Nucleus

Sub-Atomic Particles
  • Proton charged molecule in nucleus
  • Written as p
  • Mass of 1.67 x 10-27
  • Neutron a neutral particle in nucleus (NO
  • Written as n
  • Mass of 1.67 x 10-27

  • Electron a - charged particle moving around
    the outside of nucleus in an electron cloud
    think of fan blades
  • Written as e-
  • Mass of 9.11 x 10-31. Very little mass
  • Atoms have no overall charge because they have an
    equal number of protons and electrons.

Electron Cloud Orbitals
  • It is impossible to know the exact location of a
    given electron in its electron cloud.
  • So we have a general area based on an electrons
    energy level. General rule the more energy an
    electron has, the farther from the nucleus and
    the positive protons it can get.

  • Orbitals a region in an atom where there is a
    high probability of finding electrons we only
    look at two types, there are more.
  • S-orbitals are spherically shaped
  • Holds first two electrons of every element
  • Is the lowest energy level
  • After 1st S-orbital is full, a second fills with
    2 more e-

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  • P-orbitals are peanut shaped
  • When the 2 s-orbitals are full (4e-), the 5th
    through 10th electrons will fill p-orbitals
  • These electrons have slightly more energy than
    the first 4

Electron Clouds and Energy
  • Electrons move about the electron clouds
    (orbitals) based on their energy levels.
  • Analogy sun and planets

  • General Atomic Model
  • 1st energy level
  • s-orbital with 2e-
  • 2nd energy level
  • s-orbital with 2e-
  • 3 p-orbitals with 2e- each 6e-

  • Valence electron an electron in the outermost
    energy level of an atom
  • hydrogen has 1 helium has 2 lithium has 1
  • these are the electrons that will allow the atom
    to react with others

3-2 A Guided Tour of the Periodic Table
  • The periodic table is a visual representation of
    the elements organized by properties.
  • Each element has a symbol
  • Organized by of protons also called the atomic

  • Periodic law properties of elements tend to
    change in a regular pattern when elements are
    arranged in order of increasing atomic number, or
    number of protons in their atoms.

History of the periodic table
  • Dmitri Mendeleev (1834-1907)
  • Organized 70 known elements into a able according
    to common characteristics.
  • Problem ? there were many empty spaces and it was
    very long

  • Henry Moseley (1887-1915)
  • Determined the atomic number of elements and
    recognized Mendeleevs table to what we know today

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The Periodic Table
  • Periods are horizontal rows
  • There are 7 periods
  • The protons and electrons increases from left
    to right
  • Other properties also follow pattern including
    size of molecule

  • Groups are vertical columns
  • Also called families because elements in the same
    group share physical and chemical properties.
  • Elements in a group have the same of valence
  • Each group is identified by a number and letter

  • Atoms that do not have a filled outermost energy
    level may undergo a process called ionization.
  • The atom will either gain or lose valence
  • Example Element Lithium from Group 1 is very
    reactive. Li will give away its 3rd electron and
    become a positive ion.

  • All elements in the first group on the periodic
    table will react the same way
  • A positive ion is called a cation
  • A negative ion is called an anion

  • Each element and its information can be found in
    a box on the periodic table.
  • General format

  • Atomic number
  • Is equal to the number of protons in the nucleus
  • Will also equal the number of electrons in the
    electron cloud
  • Will always be a whole number on the table (no

  • Atomic mass
  • The mass of the nucleus of the atom
  • The combined number of protons AND neutrons in an
  • Atomic mass p n
  • Will always be the larger number

  • Protons
  • Electrons
  • Neutrons
  • Protons
  • Electrons
  • Neutrons

8 Oxygen 16
12 Carbon 6
  • Protons
  • Electrons
  • Neutrons
  • Protons
  • Electrons
  • Neutrons

4 Helium 2
5 Boron 11
  • Different versions of an element that have
    different numbers of neutrons.
  • They have the same protons, but different masses

  • This is why the average atomic masses on the
    periodic tables are decimals, the mass is a
    combination of all isotopes.
  • Ex Hydrogen has 1p, 1e-, and has a mass of
    1.007 because it is mostly found as an isotope
    with no neutron

The mass of an atom
  • It is very small, so they decided to measure a
    Carbon-12 atom (6 protons and 6 neutrons) and
    divide into 12 meaning they said each proton and
    neutron equals 1 atomic mass unit

3-3 Families of Elements
  • - How are elements classified?
  • Metals versus Nonmetals
  • Most elements are metals
  • Most metals are shiny solids that can be
    stretched and shaped
  • They are good conductors of heat and electricity

  • Nonmetals are usually on the right of the
    periodic table
  • Include solids, liquids and gases
  • Nonmetal solids are usually poor conductors of
    heat and electricity
  • Some can conduct under certain conditions

The Periodic Table
  • Metals There are 4 different groups

Alkali Metals - Group 1 (except hydrogen)
  • Soft and shiny
  • Have one valence electron forms
  • cations very easily
  • React violently with water elements are usually
    stored in oil
  • Only found in compounds in nature
  • video

Alkaline Earth Metals Group 2
  • Have 2 valence electrons
  • May react to form ions with 2 charge
  • Calcium is very important in skeletons
  • Magnesium is the lightest structural material

Transition Metals Groups 3-12
  • May lose electrons to form multiple cations
  • All conduct heat and electricity
  • Copper wire
  • Can be stretched and shaped without breaking
    gold and silver jewelry

Synthetic Elements
  • Some of the transition metals are man-made
    Tc-43, Pm-61 and Atomic numbers 93 and above
  • Many are radioactive the nuclei are continually
    decaying to produce different elements

Nonmetals all but Hydrogen are found on the
right of P. Table
  • Carbon is a very important non-metal
  • Pure state graphite, pencil lead
  • Diamond
  • In body structure

Halogens Group 17
  • Very reactive gain electron to form -1 anions
  • Chlorine is used to kill bacteria pools,
    drinking water
  • Fluorine anion prevents tooth decay

Nobel Gases Group 18
  • Exist as single atoms because they are inert or
    unreactive the outer energy level is full of
  • Neon is used in neon signs
  • Helium is less dense than air it floats

Semiconductors or metalloids 6 elements
  • Have some properties of metals
  • Under certain conditions, they can conduct heat
    and electricity
  • Silicon is very important in modern technology