Introduction to Matter

What is Matter? Matter is anything that has mass and takes up space. – Mass – the quantity of matter an object has – Volume – the amount of space an object takes up – Weight – the pull of gravity on an object Challenge Question: Can the weight of an object change without changing its mass? Matter is organized into various types of substances or mixtures

Classification of Matter Substance – a single kind of matter with a specific composition and properties Element – a substance that is made up of one type of atom – Atom – the basic particle from which all common matter is made Compound – a substance made of two or more different types of atoms/elements that are chemically bonded in a set ratio Molecule – groups of two or more atoms held together by chemical bonds. – Chemical bond – the force of attraction between two atoms – Chemical Formula – the elemental ratio of a compound (examples: H2O, NaCl, & O2 ) – All compounds are also molecules – Some molecules can also be pure elements

Mixtures Mixture – a group of two or more substances – Substances in a mixture retain their individual properties – There are two types of mixtures: Homogeneous Mixtures – Evenly mixed substances (Examples: Sweet Tea, Brass, Air, etc..) Heterogeneous Mixtures – Unevenly mixed substances (Examples: Dirt, Salad, Legos, etc..)

5 MATTER Can it be physically separated? Homogeneous Mixture (solution) Heterogeneous Mixture CompoundElement MIXTURESUBSTANCE yesno Can it be chemically decomposed? noyes Is the composition uniform? noyes ColloidsSuspensions Courtesy Christy Johannesson

Examples of Pure Substances Elemental Substances Gold (Au) Aluminum (Al) Graphite (C) Neon Gas (Ne) Oxygen Gas (O 2 ) Diamond (C) Ozone (O 3 ) Compound Substances Water (H 2 O) Salt (NaCl) Sugar (C 12 H 22 O 11 ) Baking Soda (NaHCO 3 ) Hydrogen Peroxide (H 2 O 2 ) Saltpeter (KNO 3 )

Examples of Mixtures Homogeneous Mixtures Tea Air Saltwater Rootbeer Coffee Brass Heterogeneous Mixtures Salad Sand Trail Mix Italian Dressing

What is Chemistry? Chemistry is the study of the properties of matter and how matter changes. – These properties and changes can vary depending on its composition. – All matter has two kinds of properties: Physical Properties – the characteristics of a substance that can be observed w/o changing it into another substance. Chemical Properties – the characteristics of a substance that describes its ability to change into different substances.

Measuring Matter Matter is measured by using a number scientific instruments – Weight The weight of an object is typically measured using spring scales The International System of Units (SI) for weight is Newtons (N) Most bathroom scales are really a type of spring scale that has already converted Newtons to pounds for your convenience. – Mass Since weight varies from planet to planet, triple-beam balances can measure the mass of an object regardless of location The SI unit for mass is kilograms (kg), but grams (g) are also used 1kg = 1000 g – Volume Volume can be measured by using a graduated cylinder It can also be calculated by multiplying the height x width x length The SI unit for volume is liters (L), but milliliters (mL) are also used 1L = 1000 mL

Density Density relates to the mass of an object in a given volume Often, density is expressed as the number of grams in one cubic centimeter or grams per milliliter – The density of water at room temperature is 1g/cm³ or 1g/mL – 1 cm³ = 1 mL The densities of pure substances are typically identical, regardless of amount (ex:Archimedes & the gold crown) – Examples: Fresh Water = 1.0 g/mL Saltwater = 1.02 g/mL Pure Gold = 19.3 g/mL Iron = 7.9 g/mL The density of any object can be calculated using the following formula: Density = mass/volume (D=m/v)

Changes in Matter Matter can change either physically or chemically. – Physical Change – any change that alters the form or appearance of matter, but doesn’t turn the substance into another substance Examples: – Changes in state – Change in shape or form (dissolving, filtering, breaking, bending, distilling, crushing, etc.)

Chemical Change Unlike physical changes, a chemical change produces new substances with properties different than the original substance – Examples: Combustion Electrolysis Oxidation Tarnishing

Conservation of Mass Previously, scientists believed that matter could be created or destroyed via physical or chemical change In the 1770’s, Antonine Lavoisier was the first person to experimentally prove that mass is always conserved regardless of the physical or chemical change. This concept is known as the Law of Conservation of Mass – This law will later be modified to include the conservation of energy (E=mc²)

Energy & Matter Like matter, energy is never created nor destroyed. It can only be transformed into something else. Energy is the ability to do work or cause change There are six types of energy that are related to changes in matter: 1.Thermal – the total energy of all particles in an object 2.Chemical – energy stored in the chemical bonds between atoms 3.Radiant/Electromagnetic – energy related to the movement of light, electromagnetic waves, or particles 4.Electrical – energy of charged particles moving from one place to another 5.Nuclear – energy released when atoms are split or fused together 6.Mechanical – energy related to the motion of an object

Examples of Energy Types

Thermal Energy Thermal energy is the total energy of all the particles in an object – Thermal energy always flows from warmer matter to cooler matter – When change occurs b/c thermal energy is absorbed by an object, it is called an endothermic change. (ex: melting ice) – When change occurs b/c thermal energy is released from an object, it is called an exothermic change. (ex: combustion)

Mechanical Energy Mechanical energy is the energy related to the motion of an object. There are two types of mechanical energy: – Potential Energy (PE) – the energy an object has due to its current state or position – Kinetic Energy (KE) – the energy of matter in motion

Changes in Energy Every chemical or physical change in matter includes a change in energy During a chemical change, energy can be transformed into any other type of energy Examples: Photosynthesis turns radiant energy into chemical energy Microwaves use radiant energy to increase the thermal energy of food, which is a form of chemical energy Lights turn electrical energy into radiant & thermal energy Fire turns chemical energy into radiant & thermal energy A roller coaster going down a hill turns potential energy (PE) into kinetic energy (KE)

Examples of Energy Change

How do the following change Energy?

Create your own Energy Chain Draw an illustration of a chain of energy as it changes from object to object. Label the different types of energy at each part of the chain.