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Chemistry Unit 1

Unit 1 Flashcards

QuestionAnswer
Who called the atom the 'ultimate particle?' Epicurus.
What is an atom? Smallest part of nature; building blocks; made from protons, neutrons, and electrons. They are tiny, dense spheres.
What build molecules? Atoms.
What things determine what an atom is like? Ratio, order, position, and quantity.
Can atoms be in any random order. No, it has to be specific.
What are the raw materials for an atom? Protons and neutrons.
In the mid 1800s there were only 53 known elements, how many are there now? 118.
What are the raw materials for a molecule? Atoms.
What is necessary for water to be water? Bond angle = 104.5; 2H:1O bond ratio; Oxygen is the vertex; Melting point = 0; boiling point = 100, density25 = .986g/mL.
What is a chemical formula? The way of writing a molecule (the numbers belong to the immediate left).
What is necessary for hydrogen peroxide? 2H:2O; mp=-.43; bp=152, d25=1.463g/mL; H->O bond length=98.8; O->O=145.8.
What is an unused electron? Electron not used. It floats above and are in lone pairs.
What is the bond length? The distance from nucleus to nucleus, measured in pm.
What does pm stand for? Picometers, and is 10^-12 (trillionth). Used for measuring bond length.
What is a lewis structure? Using letters instead of circles to represent a molecule.
What happens to density when temperature rises? Drops? If it rises it will go down, and will increase as the temperature drops.
What is a structural formula? Lewis structure.
What is a perspective drawing? Modified lewis structure (wedge and dash). Shows dimension.
What is a ball and stick model? Shows each atom and the bond using a stick. Good for 3D.
What is a condensed structural formula? Like lewis structure but longer. Separates it into groups for clarification.
What is a space-filling model Shows the space occupied by each atom.
What is the hydroxyl group? Makes stuff an alcohol.
What is the difference between an atom and an element? Atom = Singular Element=Plural
What is a pure substance? A substance with definite composition and definite properties.
What is definite composition and properties? Composition - Same bond length, atom count, position, ratios, central atom, orientation, percent composition Properties - Melting point, boiling point, density, specific heat are consistent. Things you ca
Is a mixture a pure substance? Why? No. It doesn't have definite composition and can be changed by physical means.
What are physical means? Color, texture, melting point, boiling point, density, shape.
Can atoms be destroyed or created? No, they can only be rearranged and separated.
What is a physical property? Chemical property? Physical = something you can observe Chemical = when bonds are broken and made.
In a chemical reaction, what happens? Bonds are broken, made, and atoms are rearranged.
What is tetrahedral? What is an example? 4-sided with bond angles of 109.5. Methane is tetrahedral.
What is balancing an equation? Satisfying the law of conservation of matter. Making it so input and output are equal.
What is the coefficient? Multiplier used to balance an equation, goes at the front of the chemical equation.
What is the before and after called? Before=reactants After=products.
How do you find molecular weight? Find the weight of all of the atoms using amu (found on periodic table).
How do you find percent composition of a molecule? Divide the atom amount by the whole and multiply by 100.
Know the dichotomous chart for matter. Okay.
What is on the left of the periodic table? The right? The middle? The left is the metals, the right nonmetals, and the bordering line are the metalloids.
What are metalloids? They are the grey area. They have two faces, metal and nonmetal.
What are some key metal characteristics? Lustrous, malleable, conductors, solid, lose electrons during reactions. If you add an acid, it will turn into a salt with hydrogen gas. If you add oxygen, it will make a brittle salt.
What are some key nonmetal characteristics? Dull, brittle, gases, insulator, gain electrons, creates gas when mixed with oxygen.
What is electronegative? It pulls electrons into its own space.
What is a mixture? Combination of pure substances, it is inconsistent. No chemical bonds, just existing together.
What is the difference between a heterogeneous and homogeneous mixture? Hetero=not even distribution Homo=even distribution
When pure substances are combined into a mixture, what physical properties of the pure substances change? None.
What is solubility? The ability to dissolve in water.
How do you separate a heterogeneous mixture? You can use a magnet, you can decant using a filter, you can use a steam bath, you can use mortar and pestle. Order matters.
What order should you separate a mixture? 1. Use a magnet. 2. Crush up using mortar and pestle. 3. Decant and filter. 4. Do steam bath.
What three things do you have when water is introduced to a heterogeneous mixture? 1. Insoluble material that is denser than water on the bottom. 2. Insoluble but not as dense which floats. 3. Soluble, mixed with the water.
How do you measure by difference? Find the mass of the beaker, and subtract that from the mass of the beaker with the substance.
Know how to separate a heterogeneous mixture. Okay.
Know how a steam bath works. Okay.
Why do you not put the evaporating dish directly on the hot plate? It causes splashing and the high energy water droplets don't form on the bottom.
What is better, centimeters or inches? Centimeters.
How do you know how many numbers to record? Find the smallest number and divide it by two. This gives you the estimated digit.
What is the estimated digit? The number that you estimate on. All the others should be positive. You cannot go past this.
The number of significant figures is determined how? The amount of certain numbers and one estimated.
What part of a meniscus do you measure? The bottom.
What is a cm³ equal to? mL, cc.
what is a mL? It is 1/1000 of a liter, pictured as a cube.
When finding density of irregular solids, what do you use? Water displacement.
How much water and substance do you use? You need enough to cover the substance and enough substance to make the water go up.
What is the factor-label method? What goes on top? Bottom? Used to convert units. The desired unit on top. How much of previous unit to get to top unit on bottom.
How much is 1 gram? 1 ounce=28.35 grams A medium sized paper clip A penny is 2.65 grams.
What is mass? Volume? Mass - how much material in a sample. Volume - space occupied.
What is a liter? A cube of 10cmx10cmx10cm.
How big is a centimeter? About the width of your pinky fingernail.
How many centimeters are in an inch? 2.5cm.
How do you find percent error? ((Observed - Actual) / Actual) x 100
How many significant figures does pi have? None, it wasn't measured. Significant figures are measured figures.
What is an exact number? Known, counted, or looked up.
If you unbend a paper clip, what is the thickness? .1cm.
What does density measure? How much mass is packed into a certain amount of space.
How can you tell something is high density? Think the opposite for low density. Big molecules, small spaces, more molecules. Probably a metal.
How do you find volume if you know density? Use the factor-label method.
Know how to use a Thiele tube. Okay.
Created by: Harrison Smith