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What is Matter?
Matter: Anything that has mass and takes up space.
Matter is made up of particles called atoms.
Let’s identify the stuff around
us that is matter
So what is Chemistry again?
Chemistry: the study of the
properties of matter and how
matter changes.
Changes in Matter
Matter can change Examples: Freeze, cut, burn, etc. 2 types of changes
1. Physical changes
2. Chemical changes
Physical Changes
Physical Change: any change that alters the form or appearance of matter, but does not make any substance in the matter into a different substance– You start and end with same thing (see below)
Examples: 1) Change of State:
Chemical Changes
Chemical Change: a change in matter that produces one or more new substances– Start and end with different substances with
different properties Usually irreversible (can’t change back) Examples: burning, rusting, milk going sour
Signs of Change
Physical– Size– Shape– Texture
Chemical– Temperature– Color– Bubbles/fizzing– Smoke– Smell
OOPS!
Did it change size, color, shape (Physical Change)?
orDid it become different matter (Chemical
Change)?
OOPS!
Did it change size, color, shape (Physical Change)?
orDid it become different matter (Chemical
Change)?
Is it a chemical or physical change?
Breaking water up by separating it into hydrogen and oxygen
•Chemical Change
•Physical Change
OOPS!
Did it change size, color, shape (Physical Change)?
orDid it become different matter (Chemical
Change)?
OOPS!
Did it change size, color, shape (Physical Change)?
orDid it become different matter (Chemical
Change)?
OOPS!
Did it change size, color, shape (Physical Change)?
orDid it become different matter (Chemical
Change)?
OOPS!
Did it change size, color, shape (Physical Change)?
orDid it become different matter (Chemical
Change)?
OOPS!
Did it change size, color, shape (Physical Change)?
orDid it become different matter (Chemical
Change)?
OOPS!
Did it change size, color, shape (Physical Change)?
orDid it become different matter (Chemical
Change)?
Weight
Weight: Measure of the force of gravity on an object.
All objects on Earth are attracted toward the center by gravity
Weight changes on different planets with different gravities
On moon, you are 1/6 of what you weigh on Earth
Mass
Mass: amount of matter in an object.
Mass does not change with location
Units of mass: grams (g) and kilograms (kg)
Volume
Volume: the amount of space that matter occupies
Units of volume: liter (L),
milliliter (mL) = cm3
Example: Can of pop is
355 mL
Volume (cont.)
Measuring Solid Objects – – 1) Measure Length, Width
and Height
Volume: L x W x H cm3
2) Drop in Graduated
Cylinder
1 milliliter (mL) = 1 cm3
Density
Density: Relationship between the mass of a material in a given volume.
D = Mass / Volume (g/cm3)
What has a higher density?– Trash bag of sand vs. Trash bag of feathers
Density (cont.)
A block of wood –– Mass = 200 g– Volume = 250 cm3
Density = 200 g / 250 cm3
= 0.8 g/cm3
Water = 1.0 g/cm3
Since Density of wood < Density of water…
Wood will float!
Solubility
Solubility: how much solute will dissolve into the solvent.
Determined by – – 1) Temperature– 2) Pressure
Homework Questions
1) What property of matter is measured in cubic centimeters?
2) How are milliliters related to liters?
3) A plastic box is 15.3 cm long, 9.0 cm wide and 4.5 cm high. What is its volume?
4) A piece of metal has a volume of 38 cm3 and a mass of 277 g.
a) What is its density?
b) Choose the identity of the metal from the following list:
Iron = 7.9g/cm3 ; Tin 7.3 g/cm3; Lead 11.3 g/cm3; Zinc 7.1 g/cm3
States of Matter: Solid
SOLID: Fixed shape, fixed volume, high density, particles extremely close together, vibrate, low energy
Solid H2O: Below 0°C
States of Matter: Liquid
LIQUID: No fixed shape, fixed volume, particles move freely, takes shape of container
Liquid H2O: Between 0-100°C
States of Matter: Gas
GAS: No fixed shape, no fixed volume, particles move freely, large distance between particles
Gaseous H2O: Above 100°C
States of Matter: Plasma (cont.)
- Found in EXTREME temperatures like the sun and stars
-Can be made by ionizing a gas
State of Matter Changes
Most substances go through a phase change when heated or cooled.
Model 1: Representations of Molecules in Three Phases
Melting
Freezing
Boiling
Condensation
Changes Between Solid and Liquid
Melting Point: temperature at which a solid changes to a liquid.
Added heat energy makes molecules vibrate faster and faster until they break free from their fixed positions
Water: 0°C
Changes Between Solid and Liquid (cont.)
Freezing Point: temperature at which a liquid turns into a solid.
Opposite of Melting Point
When heat is taken away, particles of a liquid move slower and slower and lose their energy
Water: 0°C
Changes Between Liquid and Gas
Vaporization: change from a liquid to a gas. Particles in liquid gain energy
and speed up to form a gas
Two types:
1) Evaporation: vaporization occurs
on the surface of a liquid
2) Boiling: vaporization occurs below
the surface as well as at the
surface.– Boiling Point: temperature at which
a liquid boils
Changes Between Liquid and Gas (cont.)
Condensation: the change from a gas to a liquid
Opposite of Vaporization energy Example: Dew, Clouds
Change Between Solid and Gas
Sublimation: surface particles of a solid change directly to a gas
Do not pass through liquid state Example: Dry ice = solid carbon dioxide
Day 4 – Grouping Substances
We can group substances by their physical properties. Let’s remember, some of them are:
Weight Mass Volume Density Solubility
Color Odor Shape Texture Hardness
Why do we need to group substances?
Substances may be set apart or combined Mixture: made of two or more substances Heterogeneous mixture:
the different parts can be
seen Homogenous mixture:
evenly mixed so the
different parts cannot be
seen
How can you separate mixtures?
1) Magnetic Attraction -
Example: If you had a
mixture of iron, copper,
silver pellets, you could
remove the iron with a
magnet, because copper
and silver pellets are not
magnetic metals
How can you separate mixtures?
Filtration-
Example: If you had a mixture of water, salt and sulfur, sulfur would be
removed
-Depends on solubility-
Example: Salt, sugar,
baking soda (soluble)
Flour (not soluble)
How can you separate mixtures?
Distillation: a liquid solution is boiled Substances with different boiling points will
boil at different temperatures
Evaporation: when waterevaporates, it leaves other
Substances behind
Grouping by other physical properties
Odor: Water vs. Vinegar
Conductivity: metals have varying levels of conductivity
Elements
Element: a pure substance that cannot be broken down into any other substance by a chemical reaction.
The simplest substances Each element has its own physical and
chemical properties
Homework Questions
1) How does a heterogeneous mixture differ from a homogeneous mixture?
2) Why is saltwater a mixture?
3) Imagine a beaker containing water, sand, and salt. The salt is totally dissolved in the water. The contents of the beaker are then poured through filter paper in a funnel over a flask. After 15 days, the flask contains only solid salt particles.
Sand water salt
Soluble material:
Insoluble material:
Solvent:
The Periodic Table
Periodic Table: a chart of the elements showing the repeating pattern of their properties.
The Periodic TablePatterns of properties emerged when elements were first arranged in order of increasing atomic mass.
Examples of Early Patterns in the Periodic Table
Fluorine (F) and Chlorine (Cl) are both gases that irritate the lungs and make similar compounds.
Silver (Ag) and Copper (Cu) are both shiny metals that tarnish if exposed to air.
What is Atomic Number?
Atomic Number: The number of protons in the nucleus (the center) of an atom in an element.
Helium has an atomic number of 2 because there are 2 protons in the atom’s nucleus
Atomic Mass: how much one atom weighs, in AMU (atomic mass units)
Periodic Table Boxes
Atomic number is on top
The symbol is in the middle.
– Can be one capital letter like “O” for oxygen
– Can be one capital letter and one lowercase like “Au” for gold
Element name is below that
How is the Periodic Table organized?
Period: Rows (across) are organized by atomic number
Groups or Families: Columns (down) are organized by chemical properties of the elements.
– Each column of elements share things in common like:
How they react to other substances
Ability to rust or burn Magnetic or not
What are the different sections?
Nonmetals: e.g., He Metals: e.g., Cu, Zn Metalloids: elements that have
some of the characteristics of both metals and nonmetals
e.g., B, Si, As
MetalsMost of the elements are metals and they share commonproperties: Luster: shininess Malleability: can be hammered or rolled into flat sheets or other
shapes. Ductility: can be pulled out into a long wire. Conductivity: ability to transfer heat or electricity to another
object.
Alloys
Don’t confuse pure elements like gold, silver, and copper with something called alloys.
Alloys: are mixtures or combinations of pure elements together.
– For example, brass, steel, and bronze are alloys. These are not elements because they can be broken into the elements that formed them.
– Bronze = Copper and Tin
Compounds
Compound: a pure substance made of two or more elements chemically combined.
Chemical Formula: the representation of the elements in the compound and the ratio of atoms.
Examples:
CO2 = Carbon and Oxygen
H2O= Hydrogen and Oxygen
NaHCO3 = Sodium, Hydrogen, Carbon and Oxygen
Day 6 – Simple Compounds and Chemical Formulae
Review:
Compound: a pure substance made of two or more elements chemically combined.
Chemical Formula: the representation of the elements in the compound and the ratio of atoms.
Compounds have properties that are different from the uncombined elements.
Simple Compounds
1) CO2 = 1 Carbon atom and 2 Oxygen atoms
Carbon Dioxide
2) H2O = 2 Hydrogen atoms and 1 Oxygen atom
Water
3) NaCl = 1 Sodium atom and 1 Chlorine atom
Salt
4) CO = 1 Carbon atom and 1 Oxygen atom
Carbon Monoxide
Compounds
Not compounds… He2 , O2 , N2
Two atoms, but only one element
Molecules: when two or more atoms held by a chemical bond form a larger particle.
Chemical Equations
Chemical Equation: a short way to show a chemical reaction, using symbols instead of words.
All chemical equations have a common structure: – What substance do you start with and what you end
with
Chemical Equations
Reactants: substances you have at the beginning.
Products: new substances formed after the chemical reaction.
Reactant + Reactant Product + Product
CaCO3 CaO + CO2
Conservation of Mass
Conservation of Mass Principle: During a chemical reaction, matter is not created or destroyed.
Therefore, the total mass of the reactants must equal the total mass of the products.
Closed System: matter is not allowed to enter or leave. It enables you to measure all of the matter before and after a chemical reaction.
Balancing Chemical Equations
A chemical equation MUST show the same number of each type of atom on both sides of the equation.
Reactants Products
Fe + S FeS
Acids
Acid: a substance that tastes sour, reacts with metals and other compounds, and turns blue litmus paper red.
Examples:
Hydrochloric Acid: HCl
Sulfuric Acid: H2SO4
Acids are Sour!
Fruits like lemons, oranges and limes are sour because they are acidic!
They all contain citric acid
Can you think of some other foods that may be acidic?
Indicators
Indicator: a compound that changes color when in contact with an acid or a base.
Scientists can use litmus paper to identify an acid.
ACID turns BLUE
litmus paper RED
Bases
Base: a substance that tastes bitter, feels slippery, and turns red litmus paper blue.
Opposite of Acids! Examples:
Sodium Hydroxide: NaOH
Ammonia: NH3
Taste and Feel of Bases
Bases taste bitter! Bases feel slippery!
Turns RED litmus paper BLUE!
(B=Base B=Blue)
Where can you find acids and bases?
Acids– Foods: fruits and vegetables– Body: vitamins, lactic acids, stomach acids– Home: cleaning hard surfaces– Industry: fertilizers, batteries
Bases– Food: baking soda– Home: ammonia cleaners– Industry: making cement and mortar
pH Scale
pH Scale: a range from 0 to 14 to measure if a substance is an acid or a base.
Lower than 7 is acidic Exactly 7 is neutral = pure water Higher than 7 is basic
Nucleus: the center of the atom.
The nucleus is made of two subatomic particles:
Proton: a positively charged particle inside the nucleus.
Neutron: a particle inside of the nucleus with a neutral charge.
Electrons
Electron: a negatively
charged particle outside
of the nucleus. Electrons move rapidly
in every direction in a
“cloud” outside of the nucleus. Atoms have no charge, since the negative charge of
the electron balances with the positive charge of the proton