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Earth Chemistry. Matter - is anything that has mass and takes up space The amount of matter in an object is called mass All matter has measurable properties which helps identify it. Physical properties Properties that can be observed without changing the composition of the matter - PowerPoint PPT Presentation
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Earth Chemistry
• Matter - is anything that has mass and takes up space• The amount of matter in an
object is called mass• All matter has measurable
properties which helps identify it
• Physical properties• Properties that can be
observed without changing the composition of the matter
• Examples: Color, hardness, state of matter, density
• Chemical properties• Properties that describe how
matter reacts to other substances
• Example: flammable
Matter has 4 Phases/States• Solid – particles are packed
together and only vibrate• Liquid – particles are less
packed together than solids and slide past each other
• Gas – particles are far apart and move quickly
• Plasma – similar in properties to a gas but can conduct electricity in certain conditions
• Elements•Are substance that
cannot be broken down into simpler substances by chemical means
•Each element is made of its on atom
•Are represented by a symbol
•They are organized into the periodic table
Periodic Table• It has a series of boxes that
represent each element• The parts in each box
• Atomic Number – at the top•Represents the number of protons
• Symbol – represent the name of the element
• Atomic mass – at the bottom•Represent the total number of protons plus neutrons
Oxygen
8
O15.999
Atomic Number
Atomic Mass
Symbol
Periodic Table Set Up• Rows
• Go across• The atomic number increases
by one each time you go across
• Columns (called families or groups)• Go down• Each group has a name• All elements in the same group
have the same number of valence electrons so they react similarly
• As you go down they get larger
• Atoms – the smallest unit of an element (made of mostly empty space)
• Two parts:• Nucleus
• Protons:− Have a positive charge − Mass = ~ 1 amu
• Neutrons:− No charge − Mass = ~ 1 amu
• Electron cloud• Electron:
− Have a negative charge − Mass = 9.1 x 10-31 − Force of attracted to the protons in
the nucleus hold them in place
• An elements protons can’t change or it is not the same element
• But it can change neutrons or electrons• Neutral – have equal number of
all particles• Isotopes – a different number of
neutrons • Changes the mass
• Ions – have a different number of electrons
• If extra – they have a negative charge• If fewer – they have a positive change
• Valence electrons – the electrons that are in the outer shell of an atom
• They determine:• The atoms properties• What atoms they can bond with
• The goal is to have the outer shell full (eight electron in outer shell)
• If the outer shell is full it’s called inert (or inactive) – won’t react
• When atoms bond it is chemically • Forms a compounds• Compounds have properties are
different than the elements in it• Example: Water
Representing compounds• Chemical formulas – a
combination of letters and numbers that the makeup of the compound
• Include:• Symbols • Subscripts = little numbers to
the lower right• Tells the number of atoms of that
element
• Coefficient – large number in the front
• Tells the number of molecules
Example of Chemical Formula
C6H12O6
4C6H12O6
• To show how substance react with each other we use a chemical equation• Parts of the equation
•Reactants – on the right side of the arrow (starting materials)
•Products – on the left side of the arrow (what is made)
• All equations must have the number of each type of atom on both sides of the equation
Example of Reaction
2 Ag + S Ag2S
How are the substance held together?
• Chemical bonds – forces that hold together atoms in a molecule
• Bonds can occur if electrons from different atoms are shared or transferred
Name of Bonds• Ionic – transfer electrons•Covalent – share
electrons
Ionic Verses Covalent BondsIonic Verses Covalent Bonds
Factors Affecting Reaction Factors Affecting Reaction RatesRates• Temperature• Surface area/Particle size• Concentration of solution• Pressure• Catalysts• Inhibitors
Increasing Surface AreaIncreasing Surface Area