Observing & Classifying Matter Observations: First step in the scientific method Classify by pure substance vs. mixture Classify by chemical or physical properties & changes

Resources http://www.mcwdn.org/chemist/chemist.html

Defining Matter Matter What it is: What it is not: Examples: How to measure:

Matter – Classifying by Properties and Measurement I. Matter (“Stuff of the Universe”) Definition of Matter: Anything that has mass and occupies space. a. Mass - measured in __________ b. Space (volume): measured in _____ or _____ 2. Law of Conservation of Matter:

Matter - Not Matter – Not Sure Sort the following words into 3 categories: Peanut butter Yourself Cotton fabric Plastic food wrap Time Carbon dioxide Light Water Air Energy Motion Fish An idea Garbage

What makes up matter? Make a list of 5 -10 different objects that you see in the class room What are they made of? Classify each material as: Simple Complex (made of many materials) How could we determine what each material is?

Why do we observing & classifying in chemistry? Scientists start with observations of properties. 5 senses Measurements How a material reacts with another Classify the substances Is this similar or different from another material? Can we use classification to predict uses or how it will act? Based on observations, propose a hypothesis to explain their observations

II. Properties and Changes in Matter A. Physical Properties A characteristic that can be observed or measured without changing the identity of the substance. This means: Determined by: a. ___________ _________ b. _____________ using lab equipment.

Aluminum Foil List 10 observations Demonstrate 5 changes - Verbs Descriptive words (Adjectives) Demonstrate 5 changes - Verbs Were these qualitative? Or quantitative observations? Quality (characteristic) or quantity

Aluminum foil Physical properties Physical changes

Physical Properties: We look for these words to describe Physical Changes Appearance Touch/ Feel Smell/Taste Size States of Matter

E. Chemical Properties and Change 1. The ability of a substance to undergo changes that transforms it into different substance This means: It will have a new ______________ __________________. When it changes, it will undergo a _______________ _________________.

We look for these Indicators of chemical change: 1. 2. 3. 4.

Chemical Change - Reactions http://www.kentchemistry.com/KentsDemos.htm Page 1 Sodium reacts with water Nitric Acid reacts with copper Your Observations: What indicates that a chemical reaction is taking place?

We look for these words to describe chemical change: Note: When a substance has a chemical change, it will also change _____________ _____________

Why do scientists classify?

Classifying Matter into Major Categories Pure Substances Mixtures Pure Substance is matter for which a chemical symbol or formula can be written. Mixtures of matter are not chemically bonded and can be in any proportion. Classify these examples matter Sodium Water Soil Coffee Oxygen Soup Salt Water Iron Ice Cream Nitrogen Eggs Blood Table Salt Milk Cola Air

Pure substances = Compounds : Ionic compounds metal bonded to non-metal Covalent compounds (molecules) non-metal bonded to non-metal Represented by formulas or names

Compounds: formula & name practice Type of compound Name NCl₃ Li₂O AlBr₃ MgS

Mixtures Heterogeneous: can see the parts Homogeneous: looks uniform Substances are mixed together but they do not react to form new substances . No chemical reaction Can be separated physically– such as filtering, dismantling, etc. They can be mixed in different proportions Heterogeneous: can see the parts Homogeneous: looks uniform Also called solutions (dissolve solute into the solvent) Can easily be mistaken to be a compound

Matter Pure Substance element Example compound Mixtures Homogeneous Heterogeneous

Defining Matter Matter What it is: What it is not: Examples: How to measure: