Hesi - CHEMISTRY
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Created by:
dlcrrll5 Plus on February 28, 2011
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90 terms
Terms | Definitions |
|---|---|
 Name and describe 3 states of matter | solid (has shape and volume) Liquid (has fluid and takes the shape of the container) Gas (Volume changes with change in pressure/temperature) |
| Define Homogeneous | The composition of the mixture is the same throughout (soft drink, milk, salt water) |
| Define Heterogenous | different composition in different parts of the mix ex: chex mix, rocky road, granite |
| What is the difference between chemical and physical change? | A physical change is one which no change has been made to the chemical composition of the substance. A chemical change is one which the substance is changed by breaking and forming bonds. Ex- a spoiled egg. |
| What is an element? | a substance consisting entirely of one type of atom C, O, Co, Au |
| What is a compound? | a pure substance made of two or more elements that are chemically combined CO, H2O |
| Chemical Equations | AgNO3 (aq) + KCl(aq --- AgCl (s) + KNO3 (aq) a representation of a chemical reaction that uses symbols to show the relationship between the reactants and the products |
| What is the Law of Conservation of Mass? | Mass cannot be created or destroyed during a chemical reaction. Therefore, the equation will be balanced. Same number of elements will be represented on both sides of equation. |
| What are 5 types of chemical reactions? | Synthesis Decomposition Combustion Single Replacement Double Replacement |
| Synthesis Reaction | a reaction in which two or more substances combine to form a new compound |
| Decomposition | Divorce 2NaCl ---> (split apart) 2 Na + Cl2 |
| Combustion Reaction | -a chemical reaction that occurs when a substance reacts with oxygen, releasing energy in the form of heat and light if a reactant includes (O2) and a hydrocarbon(C3H8) and the product includes CO2 and H2O- |
| Single Replacements | dumbing a boyfriend. one element replaces another element in a compound Mg + 2NaCl --->2Na + MgCl2 |
| Double Replacements | Wife swapping AB + CD ---> AD + CB |
| Atomic Number | number of protons in an element. On periodic table it is the top number. |
| Periodic table | A CHART THAT ORGANIZES ALL KNOWN ELEMENTS INTO A GRID OF HORIZONTAL ROWS (PERIODS)total of 7 AND VERTICAL COLUMNS (GROUPS OR FAMILIES) ARRANGED BY INCREASING ATOMIC NUMBER. Roman number is number of valence electrons |
| Atoms - what are they composed of? | Protons , neutrons and electrons. Protons have + charge Electrons have a Negative charge. Neutrons have no charge. |
| Mass Number | sum of protons and neutrons in an element |
| HESI HINT The nucleus (Dead center of Atom) contains protons and neutron. Electons are located in orbital clouds surrounding nucleus. The majority of volume of an atom is empty space. | ... |
| Radioactivity | emission of particles from an unstable nucleus. The particles emitted are Radiation. |
| What are three types of radiation | Alpha Betta Gamma |
| What is Alpha Radiation | Emission of Helium Ions. Contain 2 protons, 2 neutrons. Have a +2 charge. Penetration can be stopped by a piece of paper. |
| Beta Radiation | Product of Decomposition of a neutron. Composed of High energy, high speed electrons. Negatively charged and have no mass. Can be stopped by Aluminum Foil. |
| Gamma Radiation | High energy electomagnetic radiation. Gamma rays lack charge and mass. Can be stopped by several feet of concrete or several inches of lead. |
| what are two types of chemical bonds? | Ionic and covalent |
| Ionic bonds | No sharing of electrons, transfer of electrons. Formed between metals and nonmetals. |
| Covalent Bonds | Stongest of any chemical bond. Generally between nonmetals. |
| what is the difference between polar and nonpolar covalent bonds? | Nonpolar when electrons are shared equally - no pull. the greater the difference the greater the pull will be, more polarity. Polar is enequal sharing- pull |
| intermolecular forces - attractions between particles | hydrogen bonding, dipole interactions, and dispersion forces. Dipole and dispersion forces are Van der Waals forces. |
| Hydrogen bonds | Stongest of intermolecular force. attraction for a hydrogen atom by a highly electronegative element. Generally - Florine, chlorine, oxygen and nitrogen. |
| Dipole interactions | created when an electron pair in a covalent bond is shared unequally. The positive end of a dipole will be attracted to the negative end of another. It is a weak molecular force. |
| Dispension Forces | Weakest of all intermolecular forces. moving electrons within a element/compound concentrate to one side of an atom . Causes a momentary dipole |
| Moles | amt of substance that contains one gram is 6.02 x 10 23 particle of a substance. Not unlike the word dozen. the mass of one mole of a substance is the atomic mass. |
| stoichiometry | (chemistry) the relation between the quantities of substances that take part in a reaction or form a compound. For equations to be balanced, coefficients are placed in front of compounds. -Need to know how much ingredients to make a cake -Ratio problem |
| equilibrium | a chemical reaction and its reverse proceed at equal rates. Is reversible. |
| four ways to increase reaction rate | increase temperature - particles have greater kinetic energy increase surface area- more opportunity for contact increase concentrations of reactions- add a catalyst |
| concentrations | a measurement of the amount of solute that is dissolved in a given quanitity of solvent; usually expressed as mol/L . when concentration is increased, the rate of reaction is accelerated. |
| HESI hint | concentrations have a great deal to do with rate of a reaction. Ex males and females. increase the # of people/reactants means greater number of collisions will take place. |
| catalyst | accelerates a chemical reaction without itself being affected. - Lowers the activation energy -Is not used up during reaction, can be collected on reaction completion. |
| oxidation and reduction | redox. transfer of electrons from one element to another. oxidations is loss of electrons. Reduction is gain of electrons. REVIEW CHEM. |
| HESI hint | By munipulation of the quantity of acid or base in a solution, the PH can be altered. The process of neutralization occurs when an acid and a base react to produce a salt and water. Generally result is a neutral pH or a pH close to 7. |
| Acids | -Hydrogen-ion donors -produce H3O+ in agueous solutions forms hydrogen ions when dissolved in water. - they taste sour or tart, -They release H2 (g) when reacting w/ metal -Ph less than 7. |
| Base | -Produch OH- in aq solutions -Taste bitter, feel slippery. -PH greater than 7. |
| Matter | that which has mass and occupies space. Elements are the building blocks of matter. |
| physical properties of Matter | Color, odor, taste, melting point and boiling point |
| Physical change of matter | freezing,(lq to solid) melting(solid to lq) vaporization (lq to gas) condesation (gas to lq) sublimination (solid to gas) |
| scientific method | * experiment *law *theory *model |
| precision | precision is how close a series of measurements are to one another. Need more that one measure. (Ex 2.2,2.2 and 2.2 is accurate) Accuracy is how close the measurement is to true value.(correct amt is 3.3)Can be applied to a single unit. Consistently accurate.(2.0, 3.3, 2.5) accurate because one was 3.3) |
| temperature conversions | F = 32 + 9/5 (C) C= 5/9(F-32) K=C+273 |
| Density = Mass/Volume | to find the density take the mass and divide by volume Grams/mL |
| Isotopes | same number of protons, different number of neutrons. Mass number can change, But never atomic number (protons) |
| IONS | electrically charged atoms that have gained or lost electrons. Cations are positive. Anions are negative |
| Ground state | the lowest energy state of an atom |
| Electonic configuration | O= 1s2 2s2 2p4 V 1s2 2s2 2p6 3s2 3p6 4s2 3d3 Max # in each S =2 P= 6 D =10 (minus 1period) F = 14 (minus 2 period) |
| Energy is released when bonds are broken Energy is consumed when bonds are formed. | ... |
| nomenclature | Naming a compound 1. Look at table: get symbol and Charge 2. Cations 1st/ anions 2nd 3.criss cross charges and bring to bottom ex: Magnesium chloride -Mg +2 and Cl-1 criss cross Mg1Cl2 Correct: MgCl2 |
| Combination | Getting Married . Na + Cl ---> NaCl |
| Precipitation reaction | type of combination reaction --> turns to solid 2 aq -->solid |
| Dissociation | type of decomposition. starts as a solid and turns to aq solid ---> aq + aq |
| How to fine the concentration | Concentration is how much solute is in a solvent(salt in water etc.) Molarity (M)=mole/liters Problem: what is the concentration of 58.5 g of NaCl in 2L of solution? -you must find the atomic weight of the NaCl: 58.5g -Then you must convert to moles: Mass in grams/molar mass 58.5g/58.5=1 mole -M=mole/liters -M=1 mole/2 liters -now divide them -.5 moles of NaCl |
| Mass in grams (divide by) Molar mass = Moles | ... |
| Moles (times by) molar mass = Mass in grams | ... |
| Moles (times by) 6.022 x 10(23)=#of molecule (Atoms) | ... |
| #of molecules (divide by) 6.022 x 10(23)= moles | ... |
| What is the molar mass of H2SO4 | 2 H = 1g x 2 =2grams 1 S = 32g x 1= 32 grams 4 O = 16g x 4=64 grams Total = 98 grams Molar MAss |
| Stoichiometry problem: How many moles of CO2 will be produced from the reaction of 3 moles of acetylene with the excess oxygen? | 2C2H2 +5O2--->4CO2 + 2H20 -ratio is 2:4 -3/2 = X/4 -2X = 12 -2X/2 = 12/2 X=6 Answer 6 moles of CO2 |
| OXIDATION | -Loss of Electrons -Gain in oxidation #/state |
| REDUCTION | -gain in electrons -loss in oxidation #/state |
| Redox Reaction | Both oxidation & reduction occurs |
| Electronic Booking rules | 1. oxidation state of an atom is Zero 2.Oxygen = -2 (Except O2) 3. Hydrogen = +1 (Except H2) 4.Group 1A= +1 5.Group 2A = +2 6Charge on a monatomic is the charge of the ion=Al3+=3+ 7.Must add up to the over all charge of the molecule 8.Halogens group 7 = -1 **always start w/ rule 2 & 3 & save 7 for last |
| If a molecules gains electrons | -it is reduced -it is the oxidizing agent loss in oxidation number/state |
| If a molecule loses electrons | -it is oxidized -it is the reducing agent -gains in oxidation number/state |
| An example of a redox | 2Fe + O2 ---> 2FeO - 0 + 0 ---> +2 -2 -Fe loses electrons=Oxidation=reducing agent O2 gains electrons=Reduction=oxidizing agent |
| What does "at equilibrium" Mean | During a chemical reaction, reactants are forming products at the same rate that products are forming reactants |
| HESI HINT:The process of neutralization occurs when an acid and a base react to produce a salt and water. resut pH nuetral 7 or close | ... |
| Ga +3 has how many Electrons? | 28 |
| Tc w/ a mass number 98 has how many Nuetrons? | 55 |
| What is the formula for Denisty | D=M/V |
| Tell me the strongest to weakest intramolecular bonds (inside molecule) | 1. Covalent 2. Ionic 3. Hydrogen |
| Exothermic | chemical reaction in which energy is primarily given off in the form of heat |
| Endothermic | describes a reaction that absorbs energy from the surroundings |
| Water properties | high heat capacity; polar; molecules of water cling together; a great solvent; liquid at room temp; frozen water is less dense then liquid water |
| combustion | ... |
| intramolecular | bonds that hold atoms together inside a molecule |
| Types of intramolecular bonds | covalent and ionic |
| Intermolecular | existing or acting between molecules 2 molecules joining as one |
| Intermolecular forces | "van der Waals forces" 1. LDF- london (dispersion forces) (nonpolar), 2. Dipole Dipole- (polar), 3.Hydrogen bonding (polar) (NOF) |
| List from weakest to strongest intermolecular forces | Dispersion Force ( London) Dipole-Dipole Hydrogen |
| The Ph Tester Phenolphthalein; describe its color change | Turns colorless in an acidic solution will turn orange in a high acidic solution Will turn pink in a basic solution Will turn colorless again in a extremely basic solution |
| Litmus Paper | Blue Litmus will turn red if its an acidic solution Red Litmus will turn blue if its a basic solution |
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