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Ch 1 The Science of Chemistry

Learn about the properties of chemicals and the changes they can undergo. Discover the different physical states of matter and the evidence of chemical reactions. Understand the classification of matter and its physical and chemical properties.

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Ch 1 The Science of Chemistry

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  1. Ch 1The Science of Chemistry Chemistry: Properties of chemicals and the changes chemicals can undergo. Chemicals: Substance with definite composition. Pg 5 table 1 Top 8 chemicals. Chemical reaction: process, substance(s) D (change) to produce different substance(s)

  2. Physical states of matter • Physical forms of matter • Solid (s), liquid (l), gas (g) and plasma • Properties: • Solids: fixed volume and shape. Held together in a rigid structure • Liquids: fixed volume, take the shape of container. Not held together as strongly as solids --> liquids can flow. • Gases: neither fixed volume or shape. Weak attractive forces and travel at high speeds --> flow able and compressible. (gases vs. vapors) • Plasma: gases those particles are broken apart and charged.

  3. Changes of matter 2 Types: Physical and Chemical Changes • Physical change: identity of a substance does not change, usually a change of state and at times a change of color. (not always) • Chemical change: identity of substance(s) D into a new substance(s). Chemical bonds break and reform. The # and type of atoms remain constant, they have been rearranged to form new substance(s) with new properties.

  4. Reactants ---> Products • Reactants: left side, used up • Products: right side, produced • --->: yield sign. Equal sign. • Law of conservation of mass and atoms: mass & atoms reactants = mass & atoms products

  5. Evidence of chemical change • Production of a gas. • Formation of a precipitate (ppt), solid • Release or absorption of energy • Heat, light, sound, electricity • Endothermic or exothermic • Color change. ( not always) • Chemical reactions involve one or more of these evidences

  6. Matter • Anything that has mass and take-up space (volume) • Every physical object is made of matter • Volume (L): • 3-D dimensional space of an object. Volume determination by geometric formula (V = lxwxh) or water displacement. • Mass (kg): • Measure of the amount of matter in an object as measured w/ a balance. Not affected by forces • Weight (N): • Measure of the gravitational force exerted on an object. • Changes with change of location. • Force of gravity proportional to an objects mass, double mass, double weight.

  7. Units of measurements • Properties in quantitative terms. • Quantity and units. • SI units Quantity Symbol Unit Abbrev. Length l Meter M Mass m Kilogram Kg Time t Second S Temperature T Kelvin K Amount Substance n Mole Mol Electric Current I Ampere A Luminous intensity Iv Candela Cd • Base units measurements that all other units are derived from.

  8. Units of Measurements Cont… • Prefixes (power of 10): • Giga,G (109),mega, M (106), kilo, k(103),hecto, h (102), deca, da (101), deci, d (10-1), centi, c (10-2), milli, m (10-3), micro, m (10-6), nano, n (10-9), & pico (10-12) • Attach prefixes to units to make very small or large.

  9. Units • Converting units: conversion factor, ratio that is derived from the quality of two different units. (1 day = 24 hours, 100cm = 1 m) • Convert the following: • A. 253 mL to liters • B. 1258 cm to meters • C. 15 g to kilograms • D 1254 kilocalories to gigacalories. • 5.25 hrs to seconds. • Derived units: combination (multi. or divide) base units • Area (lxw) m2, volume (lxwxh) m3, weight (mxl/t2) N

  10. Properties of matter • Physical properties: characteristic of a substance that does not involve a chemical change • Ex: changes in state, dissolving, melting & boiling points, malleability, ductility, density, heat and electricity conductivity • Density: ratio of mass to volume. Units g/mL (s) & (l), g/L (g). • D = m/v. can be used to identify a substance. • Graphing vol. Vs mass data the slope is the density of matter (pg 17 figure 11)

  11. Density Problems • Determine the density of the following. • A. object that has a mass of 22.3g and volume 15.3 mL • B What would the volume of 6.22g of aluminum? • An unknown liquid has a mass of 30.6g and a volume of 52.3 mL. What is the density? • The density of gold is 19.3 g/cm3, what is the mass of 11.3 mL of gold? • The density of ice is 0.917g/mL, how much volume does 52.3g of ice occupy?

  12. Chemical properties • Properties of matter that describes a substance’s ability to participate in chemical reactions. • Ex: Flammability, Rusting, Corrosion, tarnishing, toxicity, Radioactivity, Any reaction

  13. How matter is classified • Atoms: smallest unit of an element that maintains the properties of that element. • Physically mixed or chemically joined makes-up all kinds of matter. • Classification help predict physical and chemical properties. • Pure substance: matter either an element or cpd (compound) that has definite chemical and physical properties. • Element: pure substance contains only one kind of atom. • Symbols used to identify the element. • One or two letters (first one capitalized) some derived from Greek or Latin names

  14. Classification continue • Single atom: (noble gases, metals) or molecules of one kind of element with two atoms bonded together (H2, Cl2 [HOFBrINCl]) called diatomic. • Allotropes: one of a number of different molecular forms of an element. (graphite, diamond, C60) that have different properties. • Compounds: made-up of atoms of two or more elements joined by chemical bonds. • Represented by formulas: element symbols and subscripts. (empirical or molecular) • Structural formula: how atoms are connect and shape.

  15. Mixtures • Can be separated by physical means • Combination of two or more substances that are not chemically combined. (air, salt water, alloys, muddy water) • Homogeneous mixture: uniform structure or composition through6ut. Uniform properties throughout. • Heterogeneous mixture: composed of dissimilar components. Not mixed evenly.

  16. Separation Techniques Physical Separations: • Filtration: liquid passes through filter paper but the larger particles do not. • Crystallization (Evaporation): gets ride of liquid not substance dissolved: like sugar or salt • Distillation: separates two liquids together based on different boiling points. • Magnetism: iron or other metal filings can be drawn out with a magnet. • Chromatography: separation of colors • Also can be done by density, color, picking large pieces out

  17. Separation Techniques Cont… Chemical Separations: • Chemical Reactions • Electrolysis: separating a compound with the use of electricity.

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