Balancing Chemical Equations
What is the law that states matter cannot be created or destroyed in a chemical reaction?
Law of Conservation of Matter
How many atoms are in the molecule C6H12O6?
24 atoms
What information does the atomic number of an element provide?
Define a physical property.
A characteristic of a substance that can be observed or measured without changing the identity of the substance
What is a chemical property?
Any of a material's properties that becomes evident during, or after, a chemical reaction
Balance the equation: H2+O2→H2O
2H2+O2→2H2O
In the compound 2NaCl, how many sodium and chlorine atoms are there in total?
Two sodium atoms and two chlorine atoms
Name the element with the chemical symbol O.
Oxygen
Give an example of a physical change.
Boiling water, freezing water, dissolving sugar in water, etc.
Give an example of a chemical change.
Baking a cake, digesting food, rusting of iron, milk going sour, etc.
What is the coefficient in a chemical equation? And where is it located in the equation?
A whole number placed in front of a chemical formula, indicating how many molecules or atoms of that substance are involved in a chemical reaction
What is the difference between a molecule and a compound?
A molecule is a group of two or more atoms chemically bonded together, while a compound is a substance made up of two or more different elements chemically combined
What are the three main categories of elements on the periodic table?
Metals, non-metals, and metalloids
What happens to the state of water when it freezes? What happens to its particles?
It changes from liquid to solid, particles move slower and move closer together (tightly packed)
What does it mean for a substance to combust?
It undergoes a rapid chemical reaction with oxygen, releasing heat and usually light, essentially "burning" as a result of this reaction
Balance the equation: C3H8 + O2→CO2+H2O
C3H8 + 5O2→3CO2+4H2O
Explain how to find the number of atoms in a given formula.
Look at the subscripts following each element symbol; the subscript tells you how many atoms of that element are present in the molecule, simply add up the number of atoms from each element to get the total number of atoms in the formula
What does the period number tell you about an element?
The highest energy level that the electrons in that element occupy
Describe how melting is a physical change.
It only alters the state of matter (from solid to liquid) without changing the chemical composition of the substance involved
Describe how rusting is a chemical change
When iron (metal) reacts with oxygen in the presence of moisture, it forms a new substance called iron oxide (rust), meaning the original iron atoms are rearranged to create a different compound with distinct properties, signifying a chemical reaction has occurred
Why is it important to balance chemical equations?
So the Law of Conservation of Matter can be met, all atoms equal on both sides of the equation
In the compound Al₂(SO₄)₃, how many oxygen atoms are present in one formula unit?
12 Oxygen atoms
How do you identify a noble gas on the periodic table?
Look for the elements located in the far right column, which is Group 18
What are the indicators that a physical change has occurred?
A change in size, shape, or state of matter (like melting, freezing, or boiling), a change in texture, a change in appearance without altering the chemical composition of the substance, and the ability to often reverse the change back to its original state
Why is it important to identify chemical properties in substances?
It allows us to understand how a substance will react with other substances, predict its behavior under different conditions, and ultimately make informed decisions about its safe handling