Transcript Earth Chemistry

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
O
15.999
Atomic
Number
Symbol
Atomic
Mass
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
Bonds
Factors Affecting
Reaction Rates
•
•
•
•
•
•
Temperature
Surface area/Particle size
Concentration of solution
Pressure
Catalysts
Inhibitors
Increasing Surface Area