What are chemical changes and where do they occur?
Chemical change is when matter changes and atoms rearranged to form new substances. There’s a reactant resulting in a product. Chemical reactions may occur between atoms, molecules, or compounds.
100
What are metals?
-¾ of the periodic table are metals
-Metals fill the left and center of the periodic table
-Metal: substance that is a good conductor of heat and electricity
-Melting points vary
-Useful for many purposes
100
What is salt?
Salt is a compound made of a metal and a nonmetal. Its the combination of sodium and chlorine and it makes Sodium Chloride.
100
Litmus paper turns red in ______.
An acid
200
What are the most active elements?
The most reactive family of metals is called the alkali metals. The most reactive nonmetals are the halogen family.
200
What do metals have in common?
Metals have good electrical conductivity and become good superconductors.
200
What are acids and bases?
An acid is a substance that tastes sour and turns litmus paper red. It usually has hydrogen atoms combined with other nonmetal atoms in their molecules. Their formulas usually start with H for Hydrogen.
A base is a substance that tastes bitter and turns litmus paper green. It feels slippery.
200
Nonmetallic substances are generally good _____.
Insulators
300
What are the signs of chemical change?
Cindy Phan got everyone tater tots.
Color change, precipitation, gas, energy released, temperature change, and tarnish.
300
How hard are metals?
Some are malleable and ductile. All metals vary in malleability and ductileness (I’m not sure if those are really words, but just go with it.)
300
Are all acids and bases equally strong?
There are strong acids and bases and weak acids and bases. Molecules of strong acids in solution separate into charged particles almost completely. Molecules of weak acids separate only partially into charged particles.
300
Litmus paper turns green in_____.
A base
400
Describe how photosynthesis and respiration are chemical reactions?
Photosynthesis provides us with food to eat and oxygen to breathe. The leaves of green plants are the factories where the reaction takes place. The Sun’s energy forces the atoms of the reactants to rearrange themselves into products. The products store the energy from the Sun. When you eat and breathe, you reverse photosynthesis. The reverse reaction is called respiration.
400
What are metal compounds and alloys?
Metal compounds are a combination of atoms of metals and nonmetals. An alloy is a mixture of two or more metals and nonmetals.
400
How do we use salt?
-Ancient Egyptians used salt to dry the bodies of their kings to turn them into mummies.
-preserve food
-season food
-curing meats
-baking
-dissolve ice and lowering the freezing point
400
A strong acid has a value of 0 or 1 on the _____.
pH scale.
500
Why must the total mass of the products equal the total mass of the reactants in a chemical reaction?
There is no gain or loss of atoms when reactants change into products.
500
What other ways are alloys used?
To fight corrosion, keep cutting tools sharp, and bright in sound.
500
Where is salt found?
-3.5% are sounds in the oceans
-salt is extracted from sea water by drawing it into shallow ponds.
-mined from underground deposits that may have formed when inland seas became trapped by rising land masses.
500
In a chemical reaction, the starting substances are _____.