Chemistry Medterm Revision PDF

Matter Saturday, October 12, 2024 9:30 AM in solid matter, atoms in liquid matter, atoms Chemistry is the study of properties and pack close to each pack as closely to each behavi...

Matter Saturday, October 12, 2024 9:30 AM in solid matter, atoms in liquid matter, atoms Chemistry is the study of properties and pack close to each pack as closely to each behavior of matter other and not move other as in solid but Matter is anything that has a mass and takes up (has a fixed volume they're free to move space and rigid shape). (has a fixed volume but not a rigid shape). atoms element compound molecules The Made of a Made of two Group of in gaseous matter, building unique kind or more the same atoms pack have a lot of blocks of of atom different kind atom space between them so matter of elements they're free to move (which makes gases compressible). Classification of matter Types of pure substances A physical property is a property a substance displays without changing its composition (smell, color, taste)(can be observed without changing it to another substance) elements compounds A chemical property is a property a substance shows only by changing its composition via a mixture Pure substance Cannot be broken down Can be chemically chemical change (flammability, acidity, toxicity)(can only be observed when its changed to Composed of more than one Composted of only one further by chemical seperated into elements another substance) substance and can be substance and cannot be reactions separated physically separated physically O2, Cl2, Mg H2O,CO2,NaCl An intensive property is independent of the amount (density ,temperature , boiling point) An extensive property is dependent on the amount (volume ,mass, energy) Types of mixtures Separating mixtures A physical change is a change in matter that don't change the composition of it (changes of state) Filtration distillation chromatography A chemical change is a change that result in a new substance (combustion, oxidation, homogeneous heterogeneous Solid is Uses differences of Seperated substances on decomposition) Don't have uniform Have uniform properties separated boiling points to the basis of differences in properties throughout throughout from liquid separate them into the ability of them to (solution) their components adhere to the solid surface Significant figures Salt and watter Sand and water (dyes to paper) All nonzero digits are significant (1,2,3) Zeroes between two significant figures are significant ( 105 has three sig-fig) volume temperature density Zeroes at the beginning of a number is not significant (02 has one sig-fig) Zeroes at the end of a number are significant IF there is decimal (20 has one sig-fig, K= C + 273.15 Unit : g/cm3 whereas 20. has two sig-fig) 1L=1dm3 F= 1.8C + 32 D= m/V In addition or subtraction, answers are rounded to the least significant decimal place 1mL=1cm3 Celsius scale is based on the properties of water A physical property of a substance In multiplication or division answers are rounded to the number of digits that corresponds Kelvin scale is the SI unit of temperature to the least significant figures in any of the number used in the calculation Fahrenheit scale is used in weather reports Accuracy VS precision Accuracy refers to how proximity of a measurement to the true value of a quantity Precision refers to the proximity of several measurements to each other chapter one Page 1  Atoms, molecules, and Ions Saturday, October 12, 2024 11:50 AM Dalton's atom theory Law of conservation of mass Patterns in oxyanion nomenclature Acid nomenclature Each element if composed of extremely small particles called atoms The mass of substances present at the end of a chemical process is the ClO- : hypochlorite NO- : hyponitrite If the anion in the acid ends in -ide , change the ending to -ic acid Atoms of a givin element are identical to one another same as the mass of substances present before the process took place ClO2- :chlorite NO2- :nitrite -HCl : hydrochloric acid The atoms of one element is different from the atoms of all other ClO3- :chlorate NO3- :nitrate -HBr: hydrobromic acid elements ClO4- :perchlorate NO4- :pernitrate If the anion in the acid ends in -ite , change the ending to -ous acid Atoms are neither created nor destroyed in chemical reactions Discovery of subatomic particles -HClO : hypochlorous acid Atoms of more than one elements combine to form compounds -HClO2 : chlorous acid If the anion ends in -ate , change the ending to -ic acid Electrons (cathodes rays ) : negatively charged particles and J. J. Numbers in molecular compounds -HClO3 : chloric acid The nuclear Atom Thomson is credited with their discovery. Robert millikan determined -HClO4 : perchloric acid the charge on the electron radioactivity : 3 types of radiation were discovered by rutherford Mono A very small dense particle with electrons outside of it - particles: positively charged Di Nomenclature of binary compounds Most of the volume is empty space -b particles: negatively charged Tri Atoms are very small -g rays: uncharged Tetra Atomic and molecular weight can be measured using a mass Rutherford used  Rays to discover the nucleus Penta The ending on the second element changed to -ide spectrometer Other subatomic particles (protons and neutrons) were discovered Hexa -CO2 : carbon dioxide Masses of atoms are compared to the carbon atom with 6 protons Electrons=-protons (in charge) Hepta -CCl4 : carbon tetrachloride and 6 neutrons Neutrons have no charge Octa If the prefix ends with a or o and the name of the element Electrons have the smallest mass Nona begins with a vowel, the two successive vowels are often elided deca into one -N2O5: dinitrogen pentoxide Isotopes : atoms of the same element with different Nomenclature of organic compounds masses Isotopes have different numbers of neutrons but the same number of protons Organic chemistry is the study of carbon The simplest hydrocarbons are alkanes The first part of names just listed corresponds to the number of carbons When a hydrogen in an alkane is replaces with something else ( like -OH) the name is derived from Periodic table the name of the alkane Elements are arranged in order of atomic number The rows on the periodic table are called periods The columns are called groups Elements in the same group have similar chemical properties Types of formulas Empirical formulas give the lowest whole-number ratio of atoms to each element Chemical formulas Molecular formulas give the exact number of atoms of each element in a compound Molecular compounds are composed of two or more nonmetal Ions elements (CO2) Ionic compounds are composed of (metal+nonmetal) elements (NaCl) When an atom loses or gains electrons, it becomes an Ion Diatomic molecules occur naturally as molecules containing Cations are formed when at least one electrons is lost (monatomic cations are formed two atoms (H2,N2,O2,F2,Cl2,Br2,I2) by metals) Anions are formed when at least one electron is gained (monatomic anions are formed by nonmetals) chapter two Page 2  Chemical reactions Saturday, October 12, 2024 1:30 PM stoichiometry Types of reactions The study of the mass relationship in Combination reactions :two or more substances react to chemistry form one product Decomposition reaction : one substance breaks down into two or more substances Chemical equations Combustion reactions : rapid reactions that produce a flame (often involve O2 in the air as a reactant ) Chemical equations are concise representation (g) = gas of chemical reaction (l) = liquid Combination reactions : 2Mg(s) + O 2 (g) --> 2MgO(s) Reactants appear on the left side of the (s) = solid Decomposition reaction : CaCO 3(s)-->CaO(s)+CO2(g) equation (aq) = aqueous solution Combustion reactions : CH4(g)+2O2(g)-->CO2(g)+2H2O(g) Products appear on the right side of the equation Coefficients are inserted to balance the equation Percent composition : Avogadro's number : Molar mass : One mole = 6.02 ×1023 atoms The mass of 1 mol of a substance (g/mol) It is the atomic weight for the element from the periodic table Empirical and molecular formula mole= 1. Çalculate the moles (in a 100 g of the carbon) Moles × 6.02 ×1023 = formula unit 2. Devide each mole by the least mole (you should have a whole number) To find the molecular formula 3. Find the molar mass of the empirical formula 4. Devide the molar mass of the compound over the molar mass of the empirical formula 5. The answer should be a whole number 6. Multiply the subscripts by the number you get Theoretical yield Stochiometric calculation Limiting reactant calculations The maximum amount of product that can mol A=mol B Same steps in stochiometry for both substances be made Convert g A to g/mol A The least grams produced is the limiting reactant Different from the actual yield which is Multiply by moles A / moles B what one actually produces and measures Convert to g B chapter three Page 3