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Chemistry Review
Question | Answer |
---|---|
What does the atomic number of an element tell you about that element? | number of protons (and usually electrons as long as it is a neutral atom) |
How do you find the atomic mass? | atomic mass = protons + neutrons |
Majority of the mass of an element is found in the ___________. | nucleus (this is why the atomic mass is equal to the number of protons plus the number of neutrons) |
The rows on the periodic table are called__________. | periods |
The columns on the periodic table are called __________. | groups or families |
What do the groups on a periodic table tell you about that element? | Groups categorize elements that have similar properties. They also tell you how many electrons are found in the atom's outer shell (valence electrons). |
What do the periods on a periodic table tell you about that element? | The periods tell you how many electron shells are found in the element. |
Majority of elements found on the periodic table are classified as _____________. | metals (75%) |
What charge do protons have? | positive |
What charge do electrons have? | negative |
What charge do neutrons have? | none- they are neutral |
A chemical property describes..... | a substance's potential to undergo a chemical change/reaction |
A physical property describes... | characteristics of a substance that can be observed or measured without changing the composition of matter |
How can you tell when there is a chemical reaction? | a new substance is formed- there is a change in physical and/or chemical properties |
How can you tell when there is a physical reaction? | no new substance is formed, but it can change shape, size, or state of matter (solid, liquid, gas) |
Define atom. | the smallest part of an element, that still has all of the properties of that element (building block of matter) |
Define element. | A substance made up of all of the same type of atom (found on periodic table) |
Define molecule. | A substance made of two or more atoms chemically bonded together |
Define compound. | A substance made of two or more atoms of two or more different elements chemically bonded together |
Define solution. | A mixture in which a solid has dissolved in a liquid (homogenous) |
Define mixture. | A combination of substances physically combined, NOT chemically bonded together- the substances could be separated relatively easily |
Compare the molecular structure of a solid, liquid, and gas. | Molecules of a solid are closest together, molecules of a liquid have are a little less dense (more spaced out), and molecules of a gas are least dense (most space between them) Water is an exception- ice is actually less dense than water |
The "staircase" on the periodic table represents the __________ | metalloids. |
On what side of the "staircase" are metals found on the periodic table? | left |
An ice cube melting is an example of what type of change? | physical |
An ice cube melts when it reacts with table salt (NaCl) is an example of what type of change? | physical (change of state and lower freezing point), new solution/ mixture is made (salt water), water molecules did not chemically bond with salt molecules |
A bicycle rusts after being left out in the rain is an example of what type if change? | chemical- The iron is exposed to moisture and oxygen for an extended period of time. The iron atoms chemically bonds with the oxygen atoms forming iron oxide and water can speed up this process. |
Dry ice sublimating (going from a solid directly to a gas) is an example of what type of change? | physical (change of state) |
Chewing and digesting food exemplifies what type(s) of change? | physical- chewing, breaking food into smaller pieces chemical- enzymes in the body digesting the food |
When salad dressing sits on a shelf for an extended period of time, allowing layers to form, this is an example of what type of mixture? | heterogenous (samples will be different) |
Is soil an example of a heterogenous mixture or a homogenous mixture? | heterogenous (samples will be different) |
Crystal Light (the drink) is an example of what type of mixture? | homogenous (all samples will be the same) |
Is water an element, compound, or mixture? | compound |
Is gold an element, compound, or mixture? | element |
Is saline solution (salt water) an element, compound, or mixture? | mixture |
Use periodic table: How many protons does one atom of Phosphorus have in its nucleus? | 15 |
Use periodic table: How many neutrons does one atom of Phosphorus have in its nucleus? | 16 (round atomic mass up to 31 and subtract the atomic #) |
Use periodic table: How many electrons does one atom of Phosphorus have orbiting its nucleus? | 15 |
Use periodic table: How many valence electrons does one atom of Phosphorus have? | 5 (found in group 5) |
Use periodic table: How many electron shells does one atom of Phosphorus have? | 3 (found in period 3) |
Use periodic table: How many protons does one atom of Potassium have in its nucleus? | 19 |
Use periodic table: How many neutrons does one atom of Potassium have in its nucleus? | 20 (rounded atomic mass - atomic #) (39-19 = 20) |
Use periodic table: How many electrons does one atom of Potassium have orbiting its nucleus? | 19 |
Use periodic table: How many valence electrons does one atom of Potassium have orbiting in the outermost shell? | 1 (group 1) |
Use periodic table: How many shells of electrons will one atome of Potassium have? | 4 (period 4) |
Description of the color, size, shape, texture, or smell of a substance would be considered ________ properties. | physical |
Describing a substance as flammable, explosive, or corrosive would be sharing the _________ properties. | chemical |
What group on the periodic table contains the noble gasses? | group 18 |
Boiling water is an example of a _________ change. | physical - change of state (liquid to gas) |
How many protons, neutrons, electrons does one atom of Boron have? | 5 protons, 6 neutrons, 5 electrons |
Calcium and Argon both have a rounded atomic mass of 40. How is this possible if they are different elements? | One atom of calcium has 20 protons, while one atom of Argon has 18 protons. This makes them have different properties, making them different elements that happen to have the same atomic mass. |
Use Periodic Table: How many valence electrons does Arsenic have? | 5 valence electrons |
Use periodic table: How many electron shells does Gold have? | 6 electron shells |
When a chemical reaction releases thermal energy, causing temperature to increase this is called an: | exothermic reaction |
When a chemical reaction absorbs thermal energy, causing temperature to decrease this is called an: | endothermic reaction |
C2H4O2 + NaHCO3 -> NaC2H3O2 + H2O + CO2 This is the chemical equation for baking soda and vinegar. Is it balanced? How do you know? | Yes- There are 3 atoms of carbon, 1 atom of sodium, 5 atoms of hydrogen, and 5 atoms of oxygen on the reactant side and the product side of the equation. This means they are balanced. |
Why do chemical equations need to be balanced? | The Law of Conservation of Matter states that matter cannot be created or destroyed, so you should end up with the same amount of matter that you started with, it just may be re-arranged. |
C2H4O2 + NaHCO3 -> NaC2H3O2 + H2O + CO2 In this chemical equation, what are the reactants? | C2H4O2 and NaHCO3 |
C2H4O2 + NaHCO3 -> NaC2H3O2 + H2O + CO2 In this chemical equation, what are the products? | NaC2H3O2, H2O, and CO2 |
What are properties of metals? | - good conductors of electricity and heat - ductile/malleable (don't break easily) - lustrous/shiny - typically solid at room temperature |
What are properties of non-metals? | - good insulators of heat and electricity (poor conductors) - brittle - dull (not shiny) - no definite state of matter at room temperature (could be solid, liquid, or gas) |
What are properties of metalloids? | - Shiny/ lustrous (like metals) - solid at room temperature - brittle (like nonmetals) - semi-conductors (can conduct heat and electricity, but not as well as metals and not as poorly as non-metals) |