Chemestry
Analyze and interpret data on the properties of the substances before and after the substances interact to determine if a chemical reaction has occurred.
Develop a model to describe that
A) atoms combine in a multitude of ways to produce pure substances which make up all of the living and nonliving things we encounter.
Atoms are the building blocks of life.
C) Mixtures are composed of different proportions of pure substances
B) Atoms form molecules and compounds that range in size from two to thousands of atoms.
Chemical Change: A change that can't be changed back
Physical Change: A change that can be changed back
Use a model to explain that atoms are rearranged during a chemical reaction to form new substances with new properties. Explain that the atoms are all present in the products and thus the total number of atoms is conserved.
Examples of Balanced Equations. Balanced Equations help show the conservation of mass. What goes in, must come out.
H2 + O1 = H2O
The two hydrogen molecules, and the one oxygen molecule create water, which is H2O
C + O2 = CO2
One carbon atom, and two oxygen atoms create carbon dioxide, or CO2.
6CO2 + 6H2O = C6H12O6 + 6O2.
Six carbon combine with six water molecules create glucose (sugar) and six oxygen molecules.
In the case of Photosynthesis, the atoms are reacting to light. Glucose has six atoms and 36 molecules making it up.
In the equation of photosynthesis, we also have six oxygen molecules. Since the oxygen molecules and the glucose are not chemically combined, it becomes a mixture.
When you put in all the ingredients and burn them, it turns into the tasty delight that is cake.
You burn the egg, and it releases CO2
When the log is burned, the smoke that the fire releases is CO2. The reactants are the log and oxygen, and the product is heat and CO2
In the article 'Hair Color Chemistry' in a ScienceWorld article, they talk about how hair stylists will break down the melanin (a pigment in the hair) and they put in carbon dioxide, which lightens the hair. They then put in the selected dye, changing your hair color.
The pencil is now in two pieces, but it is still molecularly a pencil.
The butter went from a solid to a liquid, but it is still molecularly butter
Same here as the butter, the water went from ice (solid) to water (liquid). The appearance - the physical properties - may be different, but it is still molecularly the same.
This is an element (pure substance) because there are no other types of atoms present
This is a compound because the chemicals were bonded together to form a new substance; H2O
This is a mixture because none of the atoms are chemically combined
6CO2 + 6H2O = C6H12O6 + 6O2
There are six carbon, and twelve oxygen reacting with twelve hydrogen and six oxygen. It product is glucose (six carbon, twelve hydrogen, and six oxygen) and six pairs of oxygen molecules.
This is a chemical reaction because the carbon dioxide and the oxygen are reacting with light to make glucose and extra oxygen.
Conservation of Mass
What goes into a chemical reaction, must come out. Matter cannot be created or destroyed.
A physical property is a property that can be easily changed, and are measurable
Chemical Properties; These are the properties that CAN'T be easily changed
Appearance: the appearance (how it looks) of something can change during a chemical reaction. The marshmallow looked white and fluffy, but after it was burned you can see burnt marks on the marshmallow
Freezing/Melting Point; The freezing/melting point is the point at which something freezes or melts. When exposed to heat the butter (purple tie) melted. Then if we change the transition of ice to water to water to ice; the water freezes to ice. (Red tie)
Mass; the mass (amount) can change. Take the broken pencil. The mass of the pencil changed when you broke it in half.
Molecules are generally compounds, but can be two elements combined together also. Such as O2 and CO2 are both molecules.
Compounds are a lot like molecules. They are simply more specific than molecules
A compound is always a molecule, but a molecules is not always a compound. It is most of the time though.
Rotting: rotting is a chemical change because the chemicals are breaking down.
Oxidation: this is when a molecule reacts with oxygen. An example of this is rust. When the iron (Fe) reacts with oxygen, it becomes rust.
Flammability: Can it be set on fire? This is a chemical change because when something is set on fire the bonds of the atoms (bonds are what keep the atom together) break apart to form new substances
When two chemicals bond together it creates a new substance
C + O2 = CO2
The vacant electrons in the carbon and the two oxygen atoms are being rearranged to create CO2 - carbon dioxide
H2 + O = H2O
The chemicals in the chemical reaction are being rearranged to create water