Unit 1: Chemistry
1. Elements
An element is a basic substance made up of a single atom that cannot further be broken down. An atom is the smallest form of matter that holds the properties of an element. It is composed of subatomic particles.
Proton (+ charge)
Electron (- charge)
Neutron (neutral charge)
An element is a basic substance made up of a single atom that cannot further be broken down. An atom is the smallest form of matter that holds the properties of an element. It is composed of subatomic particles.
Proton (+ charge)
Electron (- charge)
Neutron (neutral charge)
Different Classes of Matter
2a. Element: An element is the most simple kind of matter which is composed of the same atom. It cannot be broken down chemically. An example of an element would be oxygen.
Compound: A compound is a molecule that is created by the bonding of two or more different elements. An example of a compound would be H₂O, otherwise known as water.
Mixture: A mixture is a combination of 2 or more substances that are physically combined, such as a veggie salad!
2b. Homogeneous and Heterogeneous Mixtures
A homogeneous mixture is created by components that are uniform throughout. A heterogeneous mixture is a combination of components that actually have different distributions and vary in particle sizes. A solution is classified as a homogeneous mixture.
Examples of Solutions:
Solid Solution- steel, iron
Liquid Solution- salt water
Gas Solution- air
3.
Compound: A compound is a molecule that is created by the bonding of two or more different elements. An example of a compound would be H₂O, otherwise known as water.
Mixture: A mixture is a combination of 2 or more substances that are physically combined, such as a veggie salad!
2b. Homogeneous and Heterogeneous Mixtures
A homogeneous mixture is created by components that are uniform throughout. A heterogeneous mixture is a combination of components that actually have different distributions and vary in particle sizes. A solution is classified as a homogeneous mixture.
Examples of Solutions:
Solid Solution- steel, iron
Liquid Solution- salt water
Gas Solution- air
3.
![Picture](/uploads/1/1/9/3/119318880/photo-oxygen-1l18wri.jpg?250)
The atomic number is based on the number of protons found in the element.
The element symbol represents the element.
Here is the location of the element's full name.
The atomic mass is the sum of the protons + neutrons in the element.
The element symbol represents the element.
Here is the location of the element's full name.
The atomic mass is the sum of the protons + neutrons in the element.
Metals, Metaloids, and Nonmetals 4a. The Periodic Tables below shows that metaloids are located on the staircase that splits metal (on the left) and nonmetals (on the right). |
Groups of Elements 4b. This table shows the different categories that elements are grouped in, including Alkali Metals, Alkaline Earth Metals, Transition Metals, Halogens, and Noble Gases. |
4c. What are groups?
Groups are organized from the top to the bottom. If elements are in the same group, that tells us that these elements share similar reactions and properties. They all contain the same number of valence electrons as well.
4d. What are Periods?
Periods are classified in rows, from left to right. When elements are located in the same period, that means that the elements in that certain row contain the same number of energy level shells.
4e. Properties of Metals, Metaloids, and Nonmetals
Metals- They are shiny and good conductors of heat and electricity. Not only that, but metals are malleable (pounded into sheets) and ductile (can be stretched into wires).
Nonmetals- These are poor conductors of heat and electricity. They are dull, mostly in the state of gas, and are certainly not malleable and ductile. Even solid nonmetals break easily.
Metaloids- This category includes properties of both metals and nonmetals. They can be shiny or dull, and somewhat good conductors of heat and electricity. Metaloids are ductile and malleable.
Groups are organized from the top to the bottom. If elements are in the same group, that tells us that these elements share similar reactions and properties. They all contain the same number of valence electrons as well.
4d. What are Periods?
Periods are classified in rows, from left to right. When elements are located in the same period, that means that the elements in that certain row contain the same number of energy level shells.
4e. Properties of Metals, Metaloids, and Nonmetals
Metals- They are shiny and good conductors of heat and electricity. Not only that, but metals are malleable (pounded into sheets) and ductile (can be stretched into wires).
Nonmetals- These are poor conductors of heat and electricity. They are dull, mostly in the state of gas, and are certainly not malleable and ductile. Even solid nonmetals break easily.
Metaloids- This category includes properties of both metals and nonmetals. They can be shiny or dull, and somewhat good conductors of heat and electricity. Metaloids are ductile and malleable.
4f. Summary of the Major Families
Alkali Metals: This is first group on the Periodic Table. It contains the most reactive elements in the table!
Alkaline Earth Metals: These metals are found in Group 2, the next most reactive group. These materials are unable to light on fire, have higher melting points, and are stronger. Elements in this group contain two valence electrons.
Transition Metals: Transition metals are any elements found in groups 3-12. They are all malleable an ductile, good conductors of heat and electricity, and are less reactive than alkali metals.
Halogens: Halogens are located in Group 17. They tend to form salt when reacted with other elements. They contain 7 valence electrons, and are very reactive. Halogens have relatively low melting and boiling points, and vary in color.
Noble Gases: Here is the very last group of the periodic table. Because Noble Gasses have very low reactivity, they do not bond with any other elements. They are odorless, colorless, and all conduct electricity called fluoresce.
5. A Shortcut to Valence Electrons!
The way to figure out the number of valence electrons in an element is quite simple. For instance, let us take the element of Oxygen. Oxygen is located in group 16. Now, we will cover up the 1 in 16, so we are left with 6. This indicates that Oxygen contains 6 valence electrons. The reason that valence electrons are important is because they determine the reactivity level in elements. The fewer valence electrons and element contains, the more reactive it is. Reactivity helps elements bond together, so without valence electrons, it would not be possible.
Compare & Contrast Ionic and Covalent Bonds
Ionic
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Similarities
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Covalent
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6. The Law of Conservation of Matter/Mass
I will know an EOG question is testing my knowledge of this law when a question about a chemical equation comes up.
I will know an EOG question is testing my knowledge of this law when a question about a chemical equation comes up.
![Picture](/uploads/1/1/9/3/119318880/editor/1184758-orig.gif?1524881580)
This chemical equation follows the law of conservation. Energy could be transferred, but the same amount is always balanced. Whatever goes through the equation comes out with the same components.
For example, if there are 10 grams of carbon present before an explosion, how many grams will be present after the explosion? The answer will be 10 grams, because of this law.
For example, if there are 10 grams of carbon present before an explosion, how many grams will be present after the explosion? The answer will be 10 grams, because of this law.
7.
Property |
Physical or Chemical |
Definition |
Specific Heat |
Physical |
Amount of energy needed to raise 1 gram of a substance 1 degree. |
Density |
Physical |
How heavy something is for its size, and how tightly things are packed together. |
Malleability |
Physical |
How well something can be shaped into another thing without breaking. |
Solubility |
Chemical |
How easily a substance can dissolve. |
Electrical Conductivity |
Physical |
The amount of electrical current that a material could take |
Chemical Reactivity |
Chemical |
The willingness of a substance to react with other substances. |
Flammability |
Chemical |
This is the ability of how easily a substance will burn |
Boiling Point |
Physical |
Temperature where liquid turns to gas |
Melting Point |
Physical |
Temperature where solid turns to liquid |
8a. PHYSICAL AND CHEMICAL CHANGES
A physical change and a chemical change change are very different. A physical change is a characteristic that can be observed or measured without actually changing the composition of. A chemical change can only be determined by changing the chemical identity of the substance.
8b. 4 Major Indicators of a Chemical Change
A physical change and a chemical change change are very different. A physical change is a characteristic that can be observed or measured without actually changing the composition of. A chemical change can only be determined by changing the chemical identity of the substance.
8b. 4 Major Indicators of a Chemical Change
- Color Change
- Precipitate Forms
- Gas Forms
- Temperature Change
- Melting Point- temperature where solid turns to liquid
- Freezing Point- temperature where liquid turns to solid
- Boiling Point- temperature where liquid turns to gas
9. Rate of Reaction
- Concentration= the more reactants that are added, the more that the rate is increased.
- Temperature= increased heat (energy) will increase the rate
- Surface Area of Solids= smaller chunks will react faster than 1 large piece
- Catalyst= substance that causes the reaction to occur faster but is not actually changed in reacion.
- Inhibitor= this is a substance decreases the rate of a chemical reaction