Presentation on theme: "Physical Science is the study of matter and energy."— Presentation transcript:
1Physical Science is the study of matter and energy. It is broken into two main sciences, physics and chemistryChemistry- studies the forms of matter and how it interacts and changesPhysics- studies energy and how it affects matter
2What is matter? Matter is anything that has mass and takes up space Matter has mass and volumeMass-the amount of matter in an objectVolume-the amount of space occupied by an objectHow is mass measured? How is volume measured?Mass is measured using a balanceVolume is measured using a meter stick and calculations or a graduated cylinder
3Volume How do you find the volume of a regular shaped object? (Length)(Width)(Height) = VolumeHow do you find the volume of an irregular shaped object?Place it in a graduated cylinder and observe the change in water level.1mL = 1 cm³
4Mass Mass is not the same thing as weight! Mass is also known as the measure of inertiaInertia- tendency of an object to resist a change in its state of motionMass is not the same thing as weight!Weight- measure of gravitational force exerted on an objectYour weight is different on the Moon than on Earth, but your mass is the same.Mass-constant, no matter where in the universe the object is-measured using a balance and expressed in gramsWeight-Varies, depending on where the object is in the universe-measured using a spring scale and expressed in newtons (unit of force)
5Practice using a balance and a spring scale. Remember that the units are different!
6How do we distinguish one example of matter from another? Physical Properties of MatterA Physical Property is something that can be observed or measured without changing the matter’s identity.-They help you identify a substanceExamples:Conductivity- ability to transfer heat or electricityState- solid, liquid, or gasDensity- mass per unity volume of a substanceSolubility- ability to dissolve in another substanceDuctility- ability to bend (be pulled into wire)Malleability- ability to be flattened without breakingColor- wavelengths of light reflected by the substanceHardness-resistance to bending, stretching, or flattening
7Density- describes the ratio of mass to volume. i.e. dense objects have a lot of mass squeezed into a small volumeDensity tells you what will float and what will sink.-If one object is less dense than another, it will float above it.e.g. oil and water-Why do boats float?Boats float because the overall density of the boat (including the air inside of it) is less than the density of water.
8÷ ÷ M X V D Density = Mass/Volume The units for density coincide with the equation (g/cm³ or g/mL)The density of water is 1 g/mLAnything with a density greater than one sinks. Anything with a density less than 1 floats.M÷÷XVD
9Why does density determine floating and sinking? -Force of gravity (weight) increases with mass-Buoyancy Force is equal to the volume of the liquid displacedBasically, the denser the object the greater the force of gravity and the weaker the buoyancy force.If gravity is stronger it sinks. If buoyancy is stronger it floats.
10Physical Changes- change of matter from one form to another that does not involve a chemical change. -You manipulate one of its physical properties but do not transform it into a new substanceExamples include:-Melting-Freezing-Vaporization-Stretching-Smashing-sometimes mixingPhysical changes can be undone by physical means (reshaping, adding heat etc.)
11States of MatterThere are three main states of matter, Solids, Liquid, and Gas.-A fourth, plasma, also exists but under rarer circumstances on EarthWhich state matter is in depends on the energy of the molecules and the degree of entropy.Entropy- disorder or lack of organizational structure between molecules-Entropy usually increases as energy increases-High entropy means matter cannon take a definite shape, low entropy allows for a definite shapeWhat is easier to control, a group of tired, well-behaved kids or a group of sugar-high, hyper kids?
12Solids low entropy definite shape definite volume usually low energy/temperatureCrystalline- orderly arrangement of particlesAmorphous-particles arranged in no specific pattern
13Liquid Higher entropy Indefinite shape (conforms to container) Definite volumeHigher energy/temperatureSurface Tensions- how strong particles at the surface of a liquid cling to each other.Viscosity- how much a liquid’s molecules cling to each other and their surroundings.-resistance to flow
14Gas High Entropy Indefinite shape Indefinite volume (fills all available space)High energy/temperatureVolume, and resultantly pressure on surrounding matter, increases as energy/temperature increases
16Matter moves from one state to another by adding energy. The amount of kinetic energy in a molecule (how much it is vibrating in place) is its temperature.So…adding or losing heat causes matter to move from one state to another
17How much energy a type of matter needs to change states is a physical property -liquid water can only exist between 0 and 100° Celsius, above that it changes to gas, below that it changes to iceEach state change has a name…Solid to liquid- meltingLiquid to gas- vaporization/evaporationGas to liquid- condensationLiquid to solid- freezingSolid to gas- sublimation
18What about Plasma?Plasma is similar to gas in that he has no definite shape or volume, but its particles are electrically charged or ionized.It carries so much energy that atoms are missing particles, leaving some with a positive charge and others with a negative chargeSince it is ionized, it reacts to magnetism and can be directedBecause of the overwhelming mass of stars, plasma makes up most of the matter in the universeCommon examples of plasma…-Lighting-Stars-Flames-fluorescent lamps-neon displays-plasma TVs
19Chemical Properties tell us which chemical changes will take place under certain conditions. Chemical Change-When one or more substances transform into one or more new substances with different propertiesChemical changes take place everywhere. Brainstorm a few examples…
20Chemical Properties and Changes Chemical Properties- characteristics of matter based on its ability to transform into a new form of matter, to change from one substance to another.e.g. flammability and reactivityThey can also be used to classify substances, but they are harder to observe or measure than physical propertiesFlammability is a substance’s ability to burnReactivity is a substance’s ability to combine with other substances to form new substancese.g. rusting, acid base reactions
21How do we know when a chemical change has taken place? Often the appearance (texture, color, physical state) can change. Other signs of change include…-heat-odor-fizzing and foaming-sound-lightUnlike physical changes, chemical changes are hard to reverse-You can undo some reactions by chemical means, but most of the time it is difficult
22Elements, Compounds, and Mixtures We can describe matter based on its physical and chemical properties, but how do we organize it?Pure substances- any form of matter made of uniform particlesMixture- matter made of multiple types of particles that are not chemically bound
23Pure substances are split into two categories… Elements- pure substance made up of only one type of atom-cannot be broken down into simpler substances by physical or chemical meansCompounds- pure substance made up of multiple types of atoms, chemically bound to form particles called molecules
24Elements are all made up of different types of atoms and organized according to their physical and chemical properties on the periodic table.
25The three main groups are metals, nonmetals, and metalloids Metals- shiny, malleable, conductive (to heat and electricity)Nonmetals- dull, nonconductive, usually brittle (often are gases or liquids at room temperature)Metalloids- share properties of both metals and nonmetalsNumber of protons and electrons, atomic mass, electronegativity, and polarity also affect where an element falls on the periodic table.Based on an element’s position on the periodic table and the properties of the elements around it you can usually predict its properties
26CompoundsCompounds are made of chemically bound elements, but their properties can be different than the properties of the elements that make them.dangerous elements can make harmless compounds and vice versaA type of molecule is always made up of the same ratio of its component elementsExamples- water is always 2 Hydrogen atoms and 1 oxygen-table salt is always 1 sodium atom and 1 chlorine atom
27Compounds can be broken down during a chemical change. -Sometimes they need a catalyst, sometimes they need an input of energy, and sometimes they just degrade over time.Eat a steak, its proteins are broken down into amino acids (mechanical and chemical digestion) then your body reassembles the amino acids into other proteins (translation).Can you come up with any other examples of compound breaking down or being formed?GlucoseDeoxyribonucleic acid
28MixturesYou have a mixture when two or more pure substances are blended together with no particular ratio between the amounts of each substance.Unlike compounds, they can be separated using only physical means-distillation (boiling)-centrifuging (spinning)Mixtures are categorized by how well they are mixed…
29There are three main types of mixtures, solutions, suspensions, and colloids. Solutions- mixed so well that they look like a single substance-they have two parts, the solute or substance being dissolved and the solvent or the substance in which the solute is dissolvedexamples…Suspensions- particles of the added material are large enough that they eventually settle to the bottom of the mixture.examples…Colloids- particles are evenly distributed throughout, large enough to see, but not large enough to settle to the bottom-If you shine a light through them they block some of the light.examples…
31Atoms: Theory and Structure Atoms are the smallest unit of an elementEach element is made-up of a different type of atom, distinguished by the number of the different subatomic particles that compose them.There are three subatomic particles that make-up an atomProton: + charge and large mass (1amu)Neutron: 0 charge and large mass (1amu)Electron: - charge and small massProtons and neutrons are found in the nucleus of the atom and electrons orbit around it, in what is called the electron cloud.
32John Dalton (late 1700’s)- after observing that elements combine in certain proportions to create compounds and experimenting to test his theory, he published his atomic theory.All substances are made of atoms. Atoms are small particles that cannot be created, divided, or destroyed.Atoms of the same element are exactly alike, and atoms of different elements are differentAtoms join with other atoms to form new substancesHe was close, but later research required a few changes.
331897- John Thomson discovered that atoms had negatively charged particles inside them (electrons). 1909- Ernest Rutherford discovered that atoms had to be mostly dead space with (-)electrons distantly surrounding a dense (+)nucleus.1913- Niels Bohr proposed that electrons orbit the nucleus at varying energy levels.Modern theory states that the paths of an electron cannot definitively be predicted-electrons roughly move in patterns called orbitals which coincide with their energy level, but their exact position cannot be determined.
34The different versions of an element are called isotopes All atoms of a particular element have the same number of protons in their nucleus, but the number of neutrons can vary.Carbon-12StableThe different versions of an element are called isotopes-some isotopes are radioactive, which means they decay over time
35Atomic Mass Unit (amu)- approximate mass of one proton or neutron Mass Number- number of protons and neutrons in an atomAtomic Mass- weighted average mass of the varying isotopes of an elementChlorine-35 makes up 76% of all chlorine in natureChlorine-37 makes up the other 24%How do we find the atomic mass?
36How can we revise Dalton’s Theory? All substances are made of atoms, which in turn are made of smaller particles called electrons, protons, and neutrons.They can be divided or combined (difficultly)- nuclear fusion and fissionAtoms of the same element will all have the same number of protons and electrons, but the number of neutrons and as a result the mass may vary (isotopes).Atoms do join with other atoms to form new substances (compounds)
38Color Quiz An atom is the base unit of a(n)… Black- element -Orange-compoundCan you identify the exact position of an electron?Black- yes -Orange- noThe weighted average mass of an element’s isotopes is its…Black- mass number -Orange- atomic massWho first attempted to describe atomic theory?Black- John Dalton -Orange- Ernest RutherfordWhat takes up the most an atom’s volume?Black- nucleus -Orange-Electron Cloud
39Periodic Table of Elements A table that organizes the elements according to their physical and chemical properties.An element’s position on the table, relative to those around it, makes it possible to predict its properties-atomic mass, melting temperature, electronegativity, polarity, etc.
40The periodic table is laid out in groups (vertical columns) and periods (horizontal rows) The number of valence electrons increases as you move from left to right, so elements on the left are the most positively charged and elements on the right are the most negatively charged.Groups 1-13 are positiveGroup 14 is +/-Groups are negative
41What are valence electrons? Valence electrons are electrons in the outermost shell (energy level) of an atom and are the ones involved in reacting with other atoms-they can either be transferred to or shared with another atom in forming a compoundA full shell (energy level) has 8 electrons, atoms react with other atoms to try to fill their outer shell.-Hydrogen and Helium only need 2 for a full shellIf you have 1 valence electron, is it easier to give away that electron or to get 7 more?
42Important Metals sections- Alkali metals-highly reactiveAlkaline Earth metalsTransition metalsLanthanidesActinides- all radioactive (decay over time)Important nonmetal sections-Noble Gases- nonreactiveHalogens- highly reactive, bind with metals to form saltOther elements-Elements between groups can be reactive, but they usually bond covalently rather than ionically
43Different periodic tables provide you with different information about each element, but they all at the least give you…Atomic numberAtomic massElement symbolSome element symbols are based on the element’s Latin names.Ferrum = IronAurum = Gold
44What are chemical reactions/changes? How do we know when one has happened?Why do they happen?Are atoms ever created or destroyed during chemical reactions?
45Signs of Chemical Reactions Chemical reactions often give us physical evidence to know that a reaction is taking place.Such as…Color changePrecipitate formation (forming a solid)Gas release (creating a gas)Heat (energy release)
48Compounds are represented using chemical formulas (e. g Compounds are represented using chemical formulas (e.g. H2O) and chemical reactions are represented using chemical equations.Chemical equations tell you the chemical formulas of all of the compounds involved and how many of each compound is involved.We know…-the number of each compound-The kinds of atoms involved-the number of each kind of atomThe compounds entering the reaction are called reactantsThe compounds produced in the reaction are called products
49The atoms in the reactants much equal the atoms in the products The one BIG ruleThe atoms in the reactants much equal the atoms in the productsThe Law of Conservation of Mass-Mass (matter) is neither created nor destroyed during a normal chemical or physical reactionAs a result the atoms present before a reaction must also be present after a reaction
50To balance equations and make sure that no matter is lost or created, we use coefficients. -they tell us how many of a particular compound is involved in a reaction-By adding them to one, two, or all of the compounds involved in a reaction we can be sure that the same number of atoms enter and leave a reaction.CO H2OC6H12O O26CO H2OC6H12O O2Balancing chemical equations is part of a branch of chemistry called Stoichiometry
51Color Quiz Which is not a sign of a chemical reaction? Green- breaking into pieces Orange- changing colorWhen two liquids mix and a solid forms, the solid is called a …Green- precipitate Orange- sublimationMatter can be created but not destroyed.Green- True Orange- FalseTo balance a chemical equation, we add…Green- Subscripts Orange- CoefficientsA balanced equation must have the same number of ________ on each side.Green- Atoms Orange- Compounds