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Unit 5 Section 2 Notes

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Title: Chapter 3 Section 2 Notes Author: alovallo Last modified by: Ashley LoVallo Created Date: 10/28/2009 1:37:47 PM Document presentation format – PowerPoint PPT presentation

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Title: Unit 5 Section 2 Notes


1
Unit 5 Section 2 Notes
  • A Guided Tour of the Periodic Table

2
Who is Dmitri Mendeleev? (1834-1907)
  • In 1869, Dmitri Ivanovitch Mendeléev created the
    first accepted version of the periodic table.

3
What is the Periodic Table?
  • Shows all known elements in the universe
  • Organizes elements by chemical properties

4
The Periodic Table
  • The periodic table groups similar elements
    together. This organization makes it easier to
    predict the properties of an element based on
    where it is in the periodic table.

5
Elements
  • Elements in the periodic table are represented by
    their symbols.
  • The first letter is ALWAYS capital
  • If there is a second letter, it is ALWAYS
    lowercase
  • Every element has its own unique symbol

Cu
C
Carbon
Copper
6
How is the Periodic Table Organized?
  • The elements are arranged based on the number of
    protons in the nucleus.
  • Periodic Law states that when elements are
    arranged in order of increasing atomic number,
    similarities in their properties will occur in a
    regular pattern.

7
Periods in the Periodic Table
  • Period a horizontal row of elements in the
    periodic table
  • As you move from left to right in a period, the
    number of protons and electrons increases by one
  • Elements in the same period DO NOT have similar
    properties in fact, they change greatly across
    the row
  • The first element in a period is always an
    extremely active solid. The last element in a
    period, is always an inactive gas.

8
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9
Groups or Families in the Periodic Table
  • Group or family a vertical column of elements in
    the periodic table
  • All elements in a family have the same number of
    valence electrons, so they have similar
    properties
  • For example, lithium (Li), sodium (Na), potassium
    (K), and other members of group 1 are all soft,
    white, shiny metals.
  • These elements are NOT exactly alike because they
    have different numbers of protons

10
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11
Ions
  • Ionization the process of adding electrons to or
    removing electrons from an atom
  • Ion an atom that has lost or gained one or more
    electrons and has a net electric charge
  • Cation an ion with a positive charge
  • Anion an ion with a negative charge

12
Goal of Atoms
  • All atoms want to have a FULL octet (8 e- in
    outer shell)
  • They do this by gaining, losing, or sharing
    electrons

13
Metals and Electrons
  • Metals LOSE electrons to form cations
  • Example Lithium loses one electron to become a
    lithium ion, written as Li

Second energy level can hold up to 8 e-. It is
easier to lose 1 e- than gain 7 more.
After lithium loses an electron, it has a full
outermost energy level.
2 electrons
3 electrons
14
Nonmetals and Electrons
  • Nonmetals GAIN electrons to form anions
  • Example Fluorine gains one electron to become a
    fluoride ion, written as F-

Second energy level can hold up to 8 e-. It is
easier to gain 1 e- than lose 7 more.
After fluorine gains an electron, it has a full
outermost energy level.
9 electrons
10 electrons
15
So, how do compounds form?
16
So, how do compounds form?
17
So, how do compounds form?
18
Atomic Number
  • Atomic Number how many protons are in the
    nucleus of an atom
  • Remember that ATOMS are neutral, so they have
    equal numbers of protons and electrons
  • Therefore, atomic number also tells the number of
    electrons for atoms only

19
Mass Number (Atomic Mass)
  • Mass Number the number of protons and neutrons
    in an atom
  • Mass number is ONLY protons and neutrons because
    they provide most of an atoms mass
  • The same element can have different mass numbers
    because they may have different numbers of
    neutrons.

20
Isotopes
  • Isotopes atoms of the same element having the
    same number of protons but different numbers of
    neutrons
  • Each version of the atom has the same number of
    protons and electrons

21
Isotopes
  • Some isotopes are more common than others
  • For example, protium is found most often

22
Calculating Neutrons in an atom
  • To calculate the number of neutrons in an atom,
    take mass number minus atomic number.

Mass Number - Atomic Number of Neutrons
23
Average Atomic Mass
  • In the periodic table, the atomic mass is a
    decimal because it is an average of all the
    naturally occurring isotopes
  • When calculating neutrons from average atomic
    mass, round to the nearest whole number
  • Example How many neutrons are in Zinc? (Atomic
    Number 30 Average atomic mass 65.39)
  • 65-30 35 neutrons

24
How do you read the Periodic Table?
25
Periodic Table Song
  • http//www.youtube.com/watch?vzUDDiWtFtEM
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