General Chemistry: Midterm Reviewer PDF

GENERAL CHEMISTRY: MIDTERM REVIEWER 3 ATOMS, IONS, AND MOLECULES MATTER AND ITS PROPERTIES Atoms: smallest unit of an element that retains the c...

GENERAL CHEMISTRY: MIDTERM REVIEWER 3 ATOMS, IONS, AND MOLECULES MATTER AND ITS PROPERTIES Atoms: smallest unit of an element that retains the chemical properties of that element; found 1 MATTER combined in molecules Building block of matter Anything that occupies space and has mass (solid, liquid, plasma, and gas) In zero gravity, liquids assume a spherical Molecules: two or more atoms binded in a shape discrete arrangement by strong forces called Gas takes both shape and volume of its chemical bonds. Atoms in a molecule move container around as a unit; may consist of two or more identical atoms Valance Electrons: octet rule, borrowing and gaining electrons to gain stability. - Monoatomic, diatomic, polyatomic Ions: atomic or molecular that carries an electrical charge (+ or -) Plasma: occurs in the interior of stars; Involve Change gaseous state of matter containing appreciable numbers of electrically Ionic Compounds: usually formed with charged particles that impart unique metals and non-metals properties to pasmas that distinct them from gases ( found in high-temperature environments) PARTICLE MODE OF MATTER Matter can have more than one property (e.g. clouds behave like gases but they are mixtures of air(gas) and water(liquid/solid) WHAT IS IT COMPOSED OF? 1) Leucippus, Democritus (400 BC) & John Dalton(1808): Atomos! 2) Aristotle (350 BC): Elements*! (Earth, Water, Air, Fire, and Aether) 3) Atoms a. Molecules b. Ions Mass: measure of the amount of matter; to States of Matter measure it we measure the force it takes to accelerate the object Solid: tightly compacted particles Liquid: slightly compacted particles Weight: the force that gravity exerts on an Gas: not compacted particles object Atomic: one atom Molecular: more than one atoms GENERAL CHEMISTRY: MIDTERM REVIEWER 2 COMPOSITION OF MATTER 2. Heterogenous: not uniform composition and separated through PURE SUBSTANCE AND MIXTURE physical processes(ex. salad) ❖ Pure compounds: separated by PURE SUBSTANCE chemical processes; made of only one type of particle and the structure remains homogenous Pure substances: uniform chemical composition with distinct properties 1. Elements: cannot be broken down and Suspension Heterogenous mixtures involving constitute all the ordinary matter in the at least one fluid; separate if left universe (made up of atoms) standing long enough (e.g. oil + Metals, Non-Metals. Metalloids water) Diatomic Molecules Noble Gasses Colloid Falls between a solution and a heterogeneous mixture 2. Compounds: Made up of 2 Molecules Criteria: Composed of 2 or more elements does not spontaneously chemically combined chemically in separate or settle out as definite proportions (Homogenous: time passes Water, Sugar, and Salt) Tyndall effect: Can be Acid < pH7 observed by eye Bases > pH7 (nanometer-sized Salts: Combination of Acids + particles) Tyndall effect: Particles of Bases solute and solvent are - Compounds often has to be different smaller than the elements. Diatomic ≠ Compound wavelength of the visible light ❖ (Example)Homogenous: uniform composition (solutions) Law of definite proportions: given chemical compound always contains its component MIXTURES elements in a fixed ratio regardless the substance’s mass. Mixtures: a combination of 2 or more (pure) elements/compounds 1. Homogenous (solution): uniform composition; solute dissolves in solvent(can be solid, liquid, & gas); Examples: sugar water, salt water, and gasoline - Solution: Saturated: right amount of solute in solvent Unsaturated: very few solute in solvent Supersaturated: too much solute in solvent GENERAL CHEMISTRY: MIDTERM REVIEWER 4 CLASSIFICATION OF MATTER SUMMARY Systematic way of determining classification using properties of matter Change involved Amount of matter: during measurement: 1. Physical Change: 1. Intensive characteristic we property: can observe characteristic without changing that does not composition(invol change value ves physical when amount of change: shape, substance is size, and state) changed Qualitative: color and Color odor Density Boiling point Quantitative: mass, Melting point volume, density, & temperature - Sublimation, Deposition, ATOM AND ITS ELECTRONIC STRUCTURE Evaporation, Condensation, Freezing, Melting 6 ATOM AND ITS PROPERTIES Atomos “indivisible” The smallest unit of an element that retains all chemical properties of an element Leucippus and Democritus agreed that they Change involved Amount of matter: during are composed of small, finite particles measurement: Aristotle’s idea that they were made up of elements stayed for up to 2000 years 2. Chemical 2. Extensive Change: process Property: where one or characteristic more substances that changes create value as amount something of substance is entirely new changed (involves chemical Volume reaction) Mass Weight Formation of Length gas Color change Temperature change GENERAL CHEMISTRY: MIDTERM REVIEWER 7 DEVELOPMENT OF THE ATOMIC SUBATOMIC PARTICLES THEORY 1. Michael Faraday (1834): Electricity consists 1. Law of Conservation of Mass: Mass of particles cannot be created nor destroyed (Antoine 2. George J. Stoney (1874): Electrons(unit of Lavoisier, 1789) electrical charge) are exchanged in electro-chemical reactions 2. Law of Definite Composition: 3. William Crookes (1879): cathode rays are compounds contain the same elements made of charged atoms in exactly the same proportion by mass (Joseph Proust, 1799) 4. J.J Thomson (1897): cathode rays are made of particles lighter than atoms and can be 3. Dalton’s Atomic Theory: Matter is deflected by an negative electric field composed of atoms, and elements are Atoms are divisible. Corpuscles composed of identical atoms (John (negatively charged subatomic Dalton, 1808) particles) are building blocks Matter is composed of small, ❌ indivisible particles called atoms All atoms of a given element are identical both in mass and in chemical properties. Atoms of different elements have different masses and different chemical properties ❌ Discovery of the electron: Cathode Ray generates electrons. It proved that Atoms are neither created nor electrons were deflecting it because the destroyed in chemical reactions but cathode ray generated repelled the magnet instead rearranged to yield when it was moved outside of the tube. substances that are different from those present before the change ❌ Electrons as negatively-charged particles: Atoms combine in simple, fixed, Followed the concept that like-charges repel whole-number ratios to form compounds ✅ and opposite charges attract following the charges of the magnet. 8 ATOMIC STRUCTURE DALTON’S ATOMIC MODEL Billiard Ball Model: One of the earliest atomic theories. Atomsare imagined as tiny, solid, miniature balls that are indivisible and indestructible. GENERAL CHEMISTRY: MIDTERM REVIEWER 5. Robert Millikan (1909): conducted the HANTARO NAGAOKA (1903) oil-drop experiment and determined the exact electron charge along with its mass. Saturnian Model Electrons around a particle of large mass −19 Electron’s charge: -1.6022 x 10 C −28 HANS GEIGER, ERNEST MARSDEN, & ERNEST Mass: 9.1094 x 10 g RUTHERFORD What did it do? Milikan created microscopic droplets. They initially fell due to gravity, but he soon discovered that the downward progress could be slowed or reversed by an electric field lower than the apparatus. By adjusting the electric field strength and making careful calculations, he was able to determine the specific charges. Geiger-Marsden Experiment The volume occupied by an atom must consist J.J Thomson (1897) of a large amount of empty space. A small, relatively heavy, and positively charged body (the nucleus) must be at the center of each atom. ERNEST RUTHERFORD (1907) Plum Pudding Model Negatively-charged electrons in a positively-charged sphere Nuclear Model Small positively charged nucleus (most of the mass is in the nucleus). He also discovered that the nuclei of other elements contain hydrogen nucleus as a building block named the proton. Isotopes: atoms of the same element that differ in mass GENERAL CHEMISTRY: MIDTERM REVIEWER NEILS BOHR (1913) 9 MODERN ATOMIC MODEL Based on Schrodinger’s mathematical model of waves: probability map of where electron is found Planetary Model Electrons in orbit around a nucleus (account for stability of electrons) Orbitals: 3D region in space where electrons ERWIN SCHRODINGER & WERNER are likely to be found HEISENBERG (1913) Principal Energy level: As this increases, the orbital extends further from the nucleus n=1 One 1s orbital = 2 n=2 2s orbital and three 2p orbitals = 8 n=3 3s orbital, three 3p orbitals, and five 3d orbitals = 18 Quantum Mechanical Model (accepted) Electrons most probably in this region n=4 4s orbital, three 4p orbitals, five 4d (uncertainty in location or momentum of orbitals, & seven 4f orbitals = 32 electrons) JAMES CHADWICK (1932) SUBLEVELS Number of electrons they contain s 2 p 6 d 10 f 14 SUBLEVELS Orbital: shape of 3d region in space There are neutrons in the nucleus. s spherical Atoms have a nucleus that contains protons and neutrons (electrons move around the p dumbell nucleus) d clover f flower GENERAL CHEMISTRY: MIDTERM REVIEWER to give the maximum number of unpaired electrons Atom have a nucleus that contains protons, and neutrons. Electrons move around the nucleus. 10 ELECTRON CONFIGURATION Atomic Structure Model: Electrons are probably found around the nucleus ORBITAL DIAGRAM ELECTRON CONFIGURATION OF THE PERIODIC TABLE Diagram that represents the electronic Number of the column in the s, p, d, and f structure of an atom blocks is the same as the number of electrons allowed in each sublevel Arranged according to energy level Number of columns = number of Electrons: represented by up and down electrons allowed in each sublevel arrows Order of energy level of orbitals: s