Matter Properties and Composition PDF

summary MATTER: Properties, Composition, and the Changes it Undergoes...

summary MATTER: Properties, Composition, and the Changes it Undergoes RECAP: CHEMISTRY - study of matter and its properties, the changes that matter undergoes,and the energy associated with those changes MATTER - anything that occupies space and has mass - physical material of the universe MASS VS WEIGHT BRANCHES - ↳ - mass is the measure of the quantity of matter in a sample of any material 1) Organic Chemistry: study of compounds with carbon combined with hydrogen - weight is the force of gravity acting on an 2) Inorganic Chemistry: study of all other compounds including some simpler carbon-containing objects mass & compounds (carbon monoxide, carbon dioxide, bicarbonates) 3) Analytical Chemistry: detection and amount of substances present (qualitative and quantitative) ENERGY 4) Physical Chemistry: application of mathematical theories and methods of physics - capacity to do work,transfer heat, elicit change in matter 5) Biochemistry: chemical processes in living organisms - forms: mechanical, light, heat, electrical COMPOSITION all chemical processes are accompanied by energy changes - types and amounts of simpler substances that ENERGY - make it up 1 KINETIC ENERGY PROPERTIES - energy of an object in motion - characteristics that gives a substance its identity - observable, to describe and distinguish an object 2 POTENTIAL ENERGY 1) when energy is conserved, it - energy an object possesses because of its is conserved, not destroyed position, condition, or composition 2494 2) situations of lower energy CLASSIFICATION OF MATTER - EXOTHERMIC: energy is released to the surroundings are more stable, and therefore (eg combustion (burning) reaction) favored, over situations of MATTER Let higher energy (less stable) ENDOTHERMIC: absorb energy from their surroundings (eg melting of ice) PURE - MIXTURE SUBSTANCE CHANGES OF MATTER - chemical change - change in chemical composition and identity HOMOGENOUS HETEROGENOUS ELEMENT COMPOUND indicators: of the substance 1) color change (example: ripening of fruits, rusting, 2) evolution of gas electrolysis of water) 3) formation of precipitate 4) temperature change PURE SUBSTANCE - matter that has fixed composition and distinct qualities; cannot be further broken down by physical means physical change - change in only the physical appearance - contains only one kind of particle (atoms of an element, or molecules) the substance (example: water vapor, melting of ice) atoms: building blocks of matter (unique per element) MOLECULES PROPERTIES OF MATTER - ELEMENT - smallest particle of an element or - cannot be further separated or broken down by chemical means compound that can have a stable chemical properties - how a substance may react or change to - simplest type of matter; consists of only one kind of atom form another substance independent existence (example: susceptibility to corrosion, - O2 is the simplest combination D COMPOUND of O element that can exist flammability, heat of combustion) - composed of atoms of two or more elements that are chemically as a stable form united in fixed proportions physical properties observed without any chemical alteration - - can be decomposed into their pure components by chemical means - molecules of a compound: composed to the substance of interest more than one kind of atom in a (example: color, density, melting point) MIXTURE definite ratio 1 EXTENSIVE PROPERTIES - combination of two or more substances in which the substances retain their distinct identities H20 (water - properties that depend on the amount of material - have variable composition and can be separated by physical means ↳ 2 It for every 10 - example: mass and volume - in a compound, the physical and chemical properties differ from its constituent elements (example: H20 is different from H2 and O2) 2 INTENSIVE PROPERTIES - independent of the amount of material examined homogenous: composition of the mixture is same throughout (example: solutions, alloys, air) - example: all chemical properties, color, density, reactability heterogenous: not uniform throughout; recognizably different properties (example: metal oxides, PbI2 in water, soup) STATES OF MATTER - SI UNITS - systeme internationale d unites (international system of units) ~ - solid - rigid and have definite shape; scientific system of units there are crystalline solids where individual particles occupy definite positions; length: meter (m) time: seconds (s) intesity of light: candela (cd) temperature: Kelvin (K) can be compressed very slightly with the use of enormous force; very slight expansion on heating mass: kilogram (kg) current: ampere (A) amount of substance: mole (mol) liquid - particles are confined to a given volume (same with solids); flows and assumes the shapes of its container up to the volume of the liquid; MEASUREMENTS OF MATTER - molecules are randomly oriented; 1) mass: describes the quantity of matter in an object 6) temperature: measure of hotness or coldness of an object; expansion on heating and compressibility is slight 2) weight: W gravitational force (g) x mass (m); determines direction of heat flow proportional to mass (weight will vary due to g) gas - less dense than liquids and solids; 3) density ( P ): quantity that indicates the amount per unit - HEAT is energy in transit from a region of higher volume of a sample temperature to a region of lower temperature; occupy all parts of any vessel in which they are confined to; : in g/cm3 , or g/mL, g/L (for gases) (never flows in the reverse direction spontaneously) capable of infinite expansion and are compressed easily; mass consists of empty space and individual particles are far apart P volume to Kelvin (K) K C + 273 15 4) percent composition: percent of a component in relation to the plasma at very high temperatures, atoms lose their electron, the resulting total mass of the compound to Fahrenheit ( F) 8 to Celcius ( C) C (. - F 9( C) + 32 F - 32) ·. mixture of electrons and nuclei makes up plasma mass of X % composition of X 100 % total mass of sample bose-einstein - at extremely low temperatures (near absolute zero), gases 5) specific gravity: ratio of the density of an object to the density condensate of Bose particles slow down and condense to form the of water both at the same temperature; P Bose-Einstein condensate substance - density of water is 1 000 g/mL (use unless stated) * P water  NATURAL LAWS - a general statement based on the observed behavior of matter DISCOVERY OF THE ATOMIC STRUCTURE to which no exceptions are known ELECTRON · - in 1897, J J Thomson discovered the electron after a ~ LAW OF CONSERVATION OF ENERGY: energy cannot be created nor destroyed in a chemical reaction or in a series of experiments using cathode ray tubes physical change, it can only be converted from one form to another the charge-to-mass ratio of the electron was. calculated to be -1 76 x 10 C/g ATOMIC THEORY OF MATTER - in 1909, Robert Millikan found that the charge of the ↳ ⑭ - electron is 1 602 x 10 C using the oil-drop experiment - the mass of the electron is found to be 9 10 x 10 g I LAW OF CONSERVATION OF MASS - by Antoine Lavoisier using J J Thomson s charge-to-mass ratio Y - matter is neither created nor destroyed during physical or chemical reactions - during the early 1900s, J J Thomson - total mass of reactants total mass of products proposed the Plum-Pudding Model: (1) the atom is composed of a cloud of positively-charged matter, with the weight evenly distributed in atom (2) negatively-charged electrons are LAW OF CONSERVATION OF MATTER AND ENERGY: the combined amount of matter and energy in the dispersed in this positively-charged sphere universe is fixed and constant X-RAY # - in 1895, Wilhelm Roentgen noticed fluorescence among LAW OF DEFINITE PROPORTION/COMPOSITION - by Joseph Louis Proust certain materials outside operating cathode-ray tubes - different samples of any pure compound contain the same elements in the same proportion by mass (constant composition) because of the unknown nature of this radiation, (example: CaCO3) Roentgen coined the term x-ray in the example, 10 00 g of lead (Pb) will react with 1 55 g of - ~ sulfur (S) to form exactly 11 55 g of lead (II) sulfide (PbS); , - Antoine Henri Becquerel associated x-rays with any excess from the proportion will be leftover fluorescence and wondered if naturally fluorescent materials produce x-rays (a) exposed uranium-containing fluorescent material (potassium uranyl sulfate) to sunlight and placed it on photographic plates LAW OF MULTIPLE PROPORTIONS by John Dalton - wrapped in black paper, believing that the uranium absorbed the sun s energy and emitted it as x-rays Y - if two elements A and B combine to form more than one compound, (b) amid the overcast weather, he resumed developing photographic the masses of B that can combine with a given mass of A are in the plates and saw that images were strong and clear, meaning that ratio of small whole numbers the uranium continued to emit radiation without an external source of energy (sun); hence, he discovered radioactivity RADIOACTIVITY # JOHN DALTON * father of modern atomic theory = - in 1896, Henri Bacquerel discovered that a compound of uranium spontaneously emits high-energy radiation - in 1808, he published the first "modern" ideas about the existence and nature of atoms - his ideas were based on reproducible experimental results of measurements by scientists - Marie and Pierre Curie began experiments to identify and isolate the source of radiation was the uranium atoms I ↳ DALTON S ATOMIC THEORY ⑭ led to multiple proportions 1) an element is composed of extremely small, indivisible particles called atoms - currently being rejected as atoms are composed of smaller particles 2) all atoms of a given element have identical properties (weight) that differ from those of other elements (1) gamma rays ( Y ) was discovered in 1900 by Paul Villard 3) atoms cannot be created, destroyed, or transformed into atoms of another - not affected by electric/magnetic fields, not made element via chemical or physical changes (explains conservation of mass) up of particles; extremely high penetrating power 4) compounds are formed when atoms of different elements combine with one another in small whole-number ratios (explains constant composition) (2) Ernest Rutherford revealed two types: 5) the relative numbers and kinds of atoms are constant in a given compound - alpha ( ) particles: carry two fundamental units A 2t DRAWBACKS # of positive charge, identical to He ions - beta ( B ) particles: negatively-charged particles by - indivisibility of an atom: atoms can be divided into subparticles (protons, electrons, neutrons) changes within nuclei of radioactive atoms and - atoms of the same element are similar in all aspects: some vary in masses and densities have the same properties as electrons (presence of isotopes) NUCLEAR MODEL OF ATOM # - atoms of different elements are different in all aspects: presence of isobars (same atomic mass such as argon and calcium with 40 amu) - Ernest Rutherford s (+ assistant Hans Geiger) Gold Foil 7 - atoms combine in simple whole-number ratios to form compounds: not observed in complex (or -scattering) experiment led to the discovery of the & organic compounds (like sugar C12H22O11) nucleus and proton - existence of allotropes (different structural forms of the same element): charcoal, graphite, and diamond AT MS provides isotopic nature nucleus: contains the neutrons and protons electrons: scattered a relatively large distance from the nucleus charged particles when an atom IONS A +- ↑ - MASS NUMBER # NET CHARGE loses or gain electrons ZX protons + neutrons protons - electrons (1) anions: negatively-charged ions ATOMIC NUMBER (gain of electron/s) * there exists a small region in an atom protons (2) cations: positively-charged ions called a nucleus containing the positive ↳ characteristic of an element (loss of electron/s) charge and mass of the atom (periodic table is arranged in +2) ATOMIC WEIGHT # * tiny electrons surround the positively ISOTOPES # - 1 amu or u = ( ) mass of C by definition charged nucleus, maintaining atom s& - weighted average of the masses of its isotopes neutral charge (electrically neutral) - in 1913, Frederick Soddy coined the term - - 24 1 amu 1 66054 x 10 g and 1 g 6 02214 x 10 amu = 23 "isotopes" as atoms of same element with same ↳ recall : avogadro's number - in 1932, James Chadwick discovered neutrons chemical properties but differ in radioactive (1) neutrons are neutral particles situated in the nucleus of an atom properties, leading to different weights ATOMIC MASS - also known as atomic weight; (2) neutrons have a similar mass with the protons - different number of neutrons, thus different masses weighted sum of the isotopic masses of (3) all nuclei have neutron(s) except the element H an atom times their relative abundance 235 235 Uranium-235 238 238 Uranium-238 92U or U - 92 protons - 143 neutrons 92U or U - 92 protons - 146 neutrons average atomic mass ( mass of isotope 1 )( abundance of isotope 1 ) +( mass of isotope 2 )( abundance of isotope 2 )+( mass of isotope n )( abundance of isotope n )