1 / 9

Describing Matter Ch. 2, Sections 2-3

Describing Matter Ch. 2, Sections 2-3. Ch 2, Section 2 Notes Physical Properties Each specific substance has its own combination of properties that can be used to identify the substance. A physical property of matter is information that can be observed without changing the matter’s identity

kevlyn
Download Presentation

Describing Matter Ch. 2, Sections 2-3

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Describing MatterCh. 2, Sections 2-3

  2. Ch 2, Section 2 Notes • Physical Properties • Each specific substance has its own combination of properties that can be used to identify the substance. • A physical property of matter is information that can be observed without changing the matter’s identity • Ex: hardness, texture, shape, temperature, odor, color, density, mass, magnetism • Identifying Matter • Examples of using physical properties: Does my locker have the capacity to hold all my books and my binders? - OR – Does this neon green shirt actually match the pale pink shoes that I want to wear to school? • Density • Density – the amount of matter within a given volume • A golf ball and a table-tennis ball are similar in volume, but the golf ball is more dense since it has more mass contained in the amount of space

  3. Liquid Layers • Density can cause liquids to separate within a container – see Fig.4 pg.46 • Liquids with the least amount of density will rise to the top and the most dense liquids will sink • Density of Solids • Density will change if mass or volume is changed • If mass and volume both change, will density change? • Water’s density – 1.0 g/mL – Materials with greater density will sink in water and those with less density will float. • Solving for Density • Density = Mass Volume • Possible units : g/cm3, g/mL, kg/m3, kg/L

  4. Using Density to Identify Substances • Density can be used to help identify a substance at certain temperatures and pressures. Ex: Table 1 p.47 • Physical Changes Do Not Form New Substances • A physical change is a change that alters the form or appearance of a material but does not convert the material into a new substance (change that affects 1+ physical properties) • Ex: molding a piece of silver into a different shape – material is still silver • Examples of Physical Changes • Freezing water, chopping wood, tearing paper, dissolving sugar • Matter and Physical Changes • Physical changes do not change the identity of a substance • Changing shape or state of matter – molding clay or melting butter – substance is the same • Dropping a glass that shatters into pieces

  5. Ch 2, Section 3 Notes • Chemical Properties • A chemical propertydescribes matter based on its ability to change into a new substance with different properties. • Ex: Flammability – the ability of a substance to burn • Reactivity – the ability of a substance to combine with another substance (or break down into two or more substances) and form something new • Combustibility – the ability to “…plode” • Comparing Physical and Chemical Properties • Physical properties – observable anytime (don’t change the substance) • Chemical properties – only observable when attempting to change the substance into something new, always present

  6. Characteristic Properties • The properties most useful in identifying a substance are characteristic properties. • Combination of physical and chemical properties • Ex: A piece of printer paper • Color: white Mass: 2.1 grams • Texture: smooth Flammability: yes • Odor: none Reactivity (with lemon • Shape: rectangular juice): yes • Chemical Changes and New Substances • A chemical change when one or more substances are changed into a new substance with different properties. • Chemical changes are the process! • New substances are formed • Ex: Wood to ash • Ex: Digesting food • Ex: Alka-seltzer and water to a bitter, disgusting drink that helps your tummy

  7. What Happens During a Chemical Change? • Ex: baking – different ingredients are mixed, heat is added, and something new is produced • Signs of Chemical Changes • Color change • Gas production • Change in temperature • Precipitate formed (precipitate – a solid formed from solution) • Change in overall properties • Matter and Chemical Changes • Chemical changes are much more difficult to reverse than physical changes.

  8. Physical vs. Chemical Changes • The compositionof an object or substance is the type and arrangement of matter that makes up the substance • Ex: Salt is made up of sodium and chlorine and is arranged in a 1:1 ratio. • A change in Composition • Physical changes do not change the composition of a substance. Ex: Water is made up of hydrogen and oxygen and is arranged in a 2:1 ratio. Water stays the same if it is in a liquid, gas, or solid state of matter. • Electrolysis – the use of an electric current to separate water into hydrogen and oxygen gases • Reversing Change • Most physical changes can be easily reversed, but chemical changes are very difficult to reverse. • Ex: Play-doh can be molded into shapes and then back to its original shape. • Ex: Ashes cannot be made back into wood.

  9. Density Practice Worksheet • #1 What is the density of carbon dioxide gas if .196 g occupies a volume of 100 mL? • Step 1 – Write the formula. • Density = mass volume • Step 2 – Substitute what you know • Density = .196 g 100 mL • Step 3 – Solve • Density = .oo196 g/mL

More Related