Matter: Properties and Changes Chapter 3

What is Matter? What everything is made of Matter has mass and volume

(Pure) Substance Unchanging chemical composition Elements and Compounds

Physical States of Matter Properties of the States of Matter

Physical Properties Can be determined without changing the nature of the substance

Intensive Property Does NOT depend on the amount Extensive Property Depends on the amount

Chemical Properties Describe how matter reacts, or doesn’t react, with other kinds of matter

Properties and States of Matter The properties of a substance can vary depending on its physical state

3-2 Changes in Matter

Physical Changes Alters a substance without changing its composition Also a change in State & dissolving

A Phase Change is a Physical Change From one state to another

Chemical Changes New substance(s) are formed

Evidence of Chemical Change

The Law of Conservation of Mass Mass is neither created nor destroyed during a chemical reaction

3-3 Mixtures of Matter

Mixtures Two or more substances (not chemically combined) Each substance retains its individual chemical properties The proportion can vary Air, salt water, sugar water, tap water Can be physically separated

Heterogeneous Mixture Not evenly mixed Soil, fruit salad

Homogeneous Mixture The substances are distributed the same throughout (All samples will be the same make-up) Called a solution. See page 81 Sugar or salt water

Alloy A mixture of metals

Separating Mixtures Physical processes based on the physical properties of the substances

Filtration Use of a porous barrier (filter paper) to separate a heterogeneous mixture of a solid and a liquid

Decanting Slowly pouring off a liquid and leaving the solid behind

Distillation Separate homogenous mixture by boiling Different boiling points

Crystallization A solid forms from a solution

Sublimation Solid to vapor One solid sublimates while the other does not

Chromatography Each component (colored ink) travels across the paper at different rates

3-4 Elements and Compounds

Element Can not be separated into smaller components by physical or chemical means 92 in nature Name, symbol, atomic number 75% of the mass of universe is Hydrogen

What is the human body made of?

Dmitiri Mendeleev Invented first periodic table - 1869

Mendeleev’s Periodic Table Horizontal rows – called periods Vertical columns – called groups/families Elements in the same group have similar properties

Compounds Made up of two or more different elements that are chemically combined Eg. water and sodium chloride Chemical formula, a specific ratio Subscript

Separating Compounds into components Usually requires energy (heat, electricity) Electrolysis

Properties of Compounds Different than the component elements Eg. Water and salt

The Law of Definite Proportions A chemical compound always contains the same elements in exactly the same proportions (by mass) Deals with various amounts of the same compound All compounds of a substance have the same chemical formula

Percent by Mass The percent mass of each element in a compound Percent mass = mass of element x 100 mass of compound See page 88 Different masses of a compound will have the same percent of each element

The Law of Multiple Proportions When different compounds form from the same elements, they do so in a ratio of small whole numbers Deals with different compounds made of the same element Carbon dioxide and carbon monoxide