Unit 4: Chemistry

Dalton's model of the atom

1. All matter is composed of extremely small particles called atoms 2. Atoms of a given element are the same size mass and properties and those of a different element have different sizes, mass and proportions (proven wrong due to isotopes being different) 3. Atoms can be subdivided, created or destroyed (they can, into protons, neutrons and electrons 4. Atoms for whole ratios when forming compounds 5. chemical reactions combine, separate, rearrange atoms

P.S.

Anything else, I am going to be at Farmer in the morning if you want to ask questions. Good Luck

Element vs. Compound

Compounds- A compound contains atoms of different elements chemically combined together in a fixed ratio. Compounds contain different elements in a fixed ratio arranged in a defined manner through chemical bonds. A compound can be separated into simpler substances by chemical methods/reactions. Elements- An element is a pure chemical substance made of the same type of atom. Elements cannot be broken down into simpler substances by chemical reactions

Separation techniques, Every single one I can think of and found on the internet and what property of mixtures they use

Crystallization Filtration Decantation Sublimation Evaporation (boiling point) distillation (boiling point or sometimes melting point) Chromatography (density) Centrifugation (density) Separating funnel (density) Precipitation

Separation Equipment (I am not sure about this since I don't think Farmer really went over this to my memory)

Filtration- Common ordinary filter paper (as might be used to make coffee) is inexpensive Distillation-distillation apparatus Centrifugation-a rope and a tube and spinning it in circles

Heterogeneous vs. Homogeneous

Mixtures can be either homogeneous or heterogeneous: A homogeneous mixture, sometimes called a solution, is relatively uniform in composition; every portion of the mixture is like every other portion. For example, if you dissolve sugar in water and mix it really well, your mixture is basically the same no matter where you sample it. A heterogeneous mixture is a mixture whose composition varies from position to position within the sample. For example, if you put some sugar in a jar, add some sand, and then give the jar a couple of shakes, your mixture doesn't have the same composition throughout the jar. Because the sand is heavier, there's probably more sand at the bottom of the jar and more sugar at the top.

Pure Substance vs. Mixtures

Pure substance has a definite and constant composition — like salt or sugar. A pure substance can be either an element or a compound, but the composition of a pure substance doesn't vary like in water it is always 2 hydrogen and 1 oxygen. They also can't be separated by your typical ways, like filtering it or cutting it, you need to use chemical methods, like giving something so much heat that the bonds break or separate. Mixtures are physical combinations of pure substances that have no definite or constant composition — the composition of a mixture varies according to who prepares the mixture. Although chemists have a difficult time separating compounds into their specific elements, the different parts of a mixture can be easily separated by physical means, such as filtration. For example, suppose you have a mixture of salt and sand, and you want to purify the sand by removing the salt. You can do this by adding water, dissolving the salt, and then filtering the mixture. You then end up with pure sand.

What now?

Umm, I would re-watch the really old video, Gases and How They Combine, to review anything else I didn't cover, watch some Crash Course and hope for the best cause, Farmer didn't really go over this.

Law of definite proportions

compounds have the same proportions of elements by mass no matter what Ex: H20, there will always be 2 hydrogen atoms from every single oxygen atom in water or CO2 (carbon dioxide), every carbon atom has 2 Oxygen atoms for carbon dioxide

Properties used to separate mixtures

density, melting point, boiling point

Law of multiple proportions

if two or more compounds are made up of the same elements, then the ratio of the masses of the second element combined with a certain mass of the first element is always a ratio of small whole numbers Ex: Now, let's think about a nice, classic breakfast item, which is the ham, egg and cheese sandwich. Sometimes we double up on the egg, or we double up the cheese or the ham when we feel hungry. Sometimes we just eat half the sandwich if we are in a hurry. There are many possible combinations when it comes to food. Just like different combinations are possible in food, different combinations are also possible for elements that make up compounds. Compounds are made up of atoms of different elements. There are compounds made up of the same elements, like carbon monoxide (CO) and carbon dioxide (CO2). Both compounds are made of carbon (C) atoms and oxygen (O) atoms; however, the ratios of carbon and oxygen in each compound is different. This illustrates the law of multiple proportions.

Avogadro's Hypothesis

same volume and at the same temperature and pressure, contain the same number of molecules.