Chapter 2: Elements are the building blocks of matter.

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Grade 9 ScienceUnit 1 Atoms, Elements, and
Compounds

• Chapter 2 Elements are the building blocks of
  matter.

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Elements

• A pure substance that cannot be broken down or
  separated into simpler substances.
• Made up of one kind of atom.
• More than 115 elements known about 92 occur
  naturally.Bill Nye Video Atoms and Elements

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Chemical Symbols

• One or two (sometimes 3) letters used to
  represent an element name
• Standard throughout the world
• Examples O Oxygen
• Au Gold

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Note

• If there is only one Letter in the chemical
  symbol it is always CAPITALIZED
• If there are two letters, the FIRST IS
  CAPITALIZED the second is lower case
• Example H Hydrogen
• He Helium

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Use Your Periodic Table on page 50 to Identify
the Chemical Symbols of these 20 Need to Know
Elements

• Hydrogen
• Sodium
• Potassium
• Magnesium
• Calcium
• Iron
• Nickel
• Copper
• Zinc
• Carbon

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• Nitrogen
• Oxygen
• Neon
• Helium
• Chlorine
• Silicon
• Silver
• Gold
• Mercury
• Lead

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The Periodic Table

• Organizes elements according to their physical
  and chemical properties.
• Developed by
• Dmitri Mendeleev
• in 1867.

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• Includes the elements name, symbol, atomic
  number and atomic mass.

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• ATOMIC NUMBER of Protons ( Electrons in a
  Neutral atom)
• ATOMIC MASS Average mass of the atoms of an
  element

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MASS NUMBER

• the number of Protons the number of
  Neutrons
• The ROUNDED atomic Mass

WHY?
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To find the Number of Neutrons

• Subtract the Atomic number from the rounded
  Atomic Mass!

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O
Neutrons 16 - 8 8
15.999
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Complete the Chart
Element Name Symbol Atomic Number of Protons of Electrons Atomic Mass
K
hydrogen
12
8
2
23.0
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Text Page 51
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Elements can be METALS, NON-METALS, or METALLOIDS

• Metals

• Shiny
• Malleable
• Ductile
• Usually solid

• Good conductors of heat and electricity

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• Non-metals

• Tend to be gases or brittle solids
• Dull
• Not malleable or ductile

• Poor conductors of heat and electricity

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• Metalloids

• Poor conductors of heat
• Non-malleable and not ductile

• Solids
• Shiny or dull
• May conduct electricity

Properties of both metals and non-metals.
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• The periodic table is organized into periods and
  chemical families.
• Periods the horizontal rows
• Families the vertical columns
• Elements in the same family have similar physical
  and chemical properties.
• See video clips on YouTube Periodic Table of
  Videos

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Chemical Families
Li, Na, K

• Alkali Metals Family 1

• Highly reactive with halogens
• Reactive with oxygen and water

• Low melting points
• Soft

Video
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• Alkaline Earth Metals Family 2

• Produce bright flames
• React with water

• Less reactive then alkali metals
• Burn in air if heated

Be, Mg, Ca
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• Halogens Family 17

F, Cl, Br

• Non-metals
• Highly reactive
• F is the most reactive element

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• Noble Gases Family 18

• Very stable
• Highly unreactive
• All gases

He, Ne, Ar
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• Transition Metals

• Found at the centre of the periodic table
• Complex arrangement of electrons

• Three are magnetic Fe, Co and Ni

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Families of the Periodic Table
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Questions page 59s 1-14
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Section 2.3 The Periodic Table and the Atomic
Theory page 60Bohr-Rutherford diagram
Nucleus
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Electron Filling Rules- Use the ATOMIC NUMBER
to determine the number of electrons and protons
of the element- Levels are filled from the INNER
most energy levels OUT.- The First Energy level
can hold a MAXIMUM of 2 electrons- The second
and third energy levels hold a MAXIMUM of 8
electrons
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Energy Level Periodic Trends

1. The number of Valence Electrons the Family
   Number
2. The number of Energy Levels the Period Number
3. The Maximum Number of Electrons in each Level
   the Number of elements in that Period
4. Elements in the same Family have the same number
   of Valence Electrons

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• The valence shell of the noble gases is FULL
  therefore stable.
• Gaining or losing electrons will allow atoms to
  achieve a kind of stability. Metals will lose
  electrons while non-metals will gain them.

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Questions Page 671-14