5 1 understanding matter (physical sciences)

California Leveled Science Readers (Grade 5) Content leveled readers teach science concepts, vocabulary, and reading skills – at each student’s reading level – and allow students to read and explore the wonders of nonfiction. Leveled science readers deliver science content to help address the individual needs of all students. They reinforce reading skills and strategies while promoting science understanding. Each grade 5 science reader is a richly illustrated, selfcontained little book with 10 to 14 double pages. BELOW 5.1 Building Blocks of Matter (Physical Sciences) 5.2 Changes in Matter (Physical Sciences) 5.3 Basic Structures of Organisms (Life Sciences) 5.4 MISSING 5.5 Water on Earth (Earth Sciences) 5.6 Weather (Earth Sciences) 5.7 The Solar System (Earth Sciences) ON 5.1 Understanding Matter (Physical Sciences) 5.2 How Matter Changes (Physical Sciences) 5.3 The Building Blocks of Organisms (Life Sciences) 5.4 Systems of the Human Body (Life Sciences) 5.5 Earths Hydrosphere (Earth Sciences) 5.6 How Weather Works (Earth Sciences) 5.7 Earths Solar System (Earth Sciences) ADVANCED 5.1 Atoms (Physical Sciences) 5.2 Acids and Bases at Work (Physical Sciences) 5.3 MISSING 5.4 MISSING 5.5 MISSING 5.6 Hurricanes (Earth Sciences) 5.7 The Red Planet (Earth Sciences)

Genre Comprehension Skill Text Features Science Content

• Diagrams

• Labels

• Glossary

Matter

Scott Foresman Science 5.1

Standards Preview Standard Set 1 Physical Sciences

1 Elements and their combinations

account for all the varied types of

matter in the world As a basis for

understanding this concept:

1.b. Students know all matter is made

of atoms, which may combine to form

molecules.

1.c. Students know metals have

properties in common, such as high

electrical and thermal conductivity

Some metals, such as aluminum (Al),

iron (Fe), nickel (Ni), copper (Cu),

silver (Ag), and gold (Au), are pure

elements; others, such as steel and

brass, are composed of a combination

of elemental metals.

1.d. Students know that each element

is made of one kind of atom and

that the elements are organized in

the periodic table by their chemical

properties.

1.e. Students know scientists have

developed instruments that can create discrete images of atoms and molecules that show that the atoms and molecules often occur in well-ordered arrays.

1.f. Students know differences in

chemical and physical properties

of substances are used to separate mixtures and identify compounds.

1.h. Students know living organisms

and most materials are composed of just a few elements.

1.i. Students know the common

properties of salts, such as sodium chloride (NaCl).

ISBN 0-328-23564-4

ì<(sk$m)=cdfged< +^-Ä-U-Ä-U

by Johanna Biviano

Physical Sciences

atom

atomic number

chemical property

compound

element

molecule

physical property

solution

Picture Credits

Every effort has been made to secure permission and provide appropriate credit for photographic material The

publisher deeply regrets any omission and pledges to correct errors called to its attention in subsequent editions.

Unless otherwise acknowledged, all photographs are the copyright of DK Images, a division of Pearson.

Photo locators denoted as follows: Top (T), Center (C), Bottom (B), Left (L), Right (R), Background (Bkgd).

1 ©DK Images; 7 CDC/PHIL/Corbis; 10 (R) ©DK Images; 12 ©DK Images; 13 (L) ©Philip Dowell/DK Images, (R) Getty

Images; 14 (B) ©Spencer Jones/Getty Images; 17 ©DK Images; 19 ©DK Images; 20 ©DK Images; 22 ©DK Images.

ISBN: 0-328-23564-4

Copyright © Pearson Education, Inc All Rights Reserved Printed in the United States of America

This publication is protected by Copyright, and permission should be obtained from the publisher prior to any

prohibited reproduction, storage in a retrieval system, or transmission in any form by any means, electronic,

mechanical, photocopying, recording, or likewise For information regarding permission(s), write to

Permissions Department, Scott Foresman, 1900 East Lake Avenue, Glenview, Illinois 60025.

1 2 3 4 5 6 7 8 9 10 V010 13 12 11 10 09 08 07 06

by Johanna Biviano

Properties of Matter

In the mid-1800s, the Gold Rush brought people from all

over the world to California Miners were looking for nuggets

of gold like the one below The gold they were hoping to fi nd

is a basic kind of matter called an element Elements are the

building blocks of matter They cannot be broken down into

smaller pieces

Out of more than 100 elements, only a few exist in nature in

a pure form Gold is one of them In fact, most matter is made

up of groups of elements Almost all of Earth’s crust is made

up of eight elements They are oxygen, silicon, aluminum, iron,

calcium, sodium, potassium, and magnesium Most living and

nonliving things are made up of a few elements that combine in

several ways

Gold is an element.

3

Elements have distinct properties from one another They

have physical properties that can be seen or measured without

changing the material A physical property is often obvious to one of your fi ve senses Color, odor, and hardness are physical properties There are different tools you can use to measure physical properties These include metersticks, balances, and spring scales Electron microscopes help scientists look at the

structure of elements An element’s chemical properties have

more to do with how an element reacts with other elements

This balance is one tool that can measure physical properties.

Physical Properties

You can tell a lot about an element’s physical properties

by looking at it and touching it From the picture of silver, you

can see that it is gray and shiny If you could touch it, it would

feel solid The color and phase of matter (solid, liquid, gas) are

physical properties

Silver also has mass and weight You can measure silver

to fi nd its mass Finding the mass with a balance will tell you

how much matter is in an object The weight of silver can be

determined with a spring scale This piece of silver will always

have the same mass, but its weight can change Weight is a

measure of how much gravity affects an object Let’s say this

silver weighs six pounds at sea level On the Moon, where there

is less gravity, it would only weigh one pound! Magnetism,

the temperatures at which a substance boils and freezes, and a

substance’s ability to dissolve are all physical properties

Silver is a pure element.

5

Chemical Properties

Using chemical properties is a useful way to identify substances Chemical properties can be seen when you combine one substance with another

Remember that iron turns to rust when it is combined with water and oxygen This is a chemical property of iron Iron

is easy to bend and shape This is a physical property called malleability Bending iron doesn’t create a chemical reaction, but adding oxygen and water does Another chemical property is

fl ammability This is the ability of a substance to burn

Oxygen and water cause iron to rust

Parts of Matter

An atom is the smallest particle of an element that has the

same properties of the element The atoms in one element are

different from the atoms in another element The structure of

atoms determines the chemical and physical properties of an

element It also shows how an element can combine with other

elements

Pure metals, such as silver, are made up of only one kind of

atom This means they are made up of only one element If you

could break silver into its smallest possible parts, you would have

one tiny atom of pure silver

An atom has smaller parts that make up its structure The

nucleus, or center of the atom, has a combination of protons and

neutrons Protons have positive electric charges, and neutrons

have no charge The number of protons in a nucleus is unique

to each element The number of protons is an element’s atomic

number An atom also has electrons Each electron has a

negative charge, and atoms can lose or gain electrons without

changing the element Some electrons can be shared with

other atoms

Many substances are not pure Instead they are made up of several atoms from one or more elements When atoms combine, they form

molecules A molecule is

the smallest possible part

of a substance made from more than one atom It has the properties of that substance

A molecule can have atoms from one element or atoms from several different elements The air we breathe has different molecules The oxygen molecules in the air are groupings of two atoms of the same element Other gases in air, such as carbon dioxide, have atoms of different elements

Scientists today have come a long way in their understanding of atoms and matter They have developed technologies that help them make images of atoms and molecules These images show that atoms and molecules are often well-ordered in a grid-like pattern

Scientists use powerful microscopes to look at parts of matter that are too small to be seen with other microscopes.

The Periodic Table of Elements

The periodic table of elements is a tool for organizing the

known elements The table starts with the smallest atomic

number in the fi rst row and increases from left to right Each

column in the table organizes elements by shared chemical

properties You can predict the properties of an element if you

know which column it is in

Each element has a short symbol with a capitalized fi rst

letter These symbols are used in chemical formulas For

example, the H stands for hydrogen and Ca stands for calcium

Periodic Table

Metalloids (semimetals) Nonmetals

9

Each element has a unique number of protons and electrons

They give each element its properties Scientists sort elements into three groups according to their properties: metals,

nonmetals, and metalloids

Metals are often good conductors of electricity, are solid

at room temperature, and are ductile, meaning they can be stretched without breaking Nonmetals are identifi ed by their brittleness, their inability to conduct heat or electricity well, and their tendency to break if stretched The third group, metalloids, includes elements that share properties of metals and nonmetals

Close-Up: Titanium

Symbol: Ti

Name: Titanium

Atomic Number: 22

10

Using the Periodic Table

The periodic table is a useful tool for understanding

elements, and it is full of information about each one You only

need to know how to read it The block for titanium, shown

below, shows you the type of information you can fi nd about

any element in the periodic table

Rows show increasing atomic weight, while columns show

similar properties The table comes together in a regular pattern,

so you can predict an element’s properties based on its location

Titanium is a strong metal that

is very light

11

Each column in the table is a group or a family Each family includes elements with similar characteristics They react with substances in similar ways

Group 1 includes metal elements that react strongly with water Hydrogen is an exception; it is a gas Its atomic structure

is similar to other elements in its family But its chemical properties are different

Rows in the periodic table are periods They are not grouped by similar characteristics The element farthest to the left is very reactive The elements become less active as you move to the right

If you look at the groups below, the color of the blocks indicates that the metallic elements on the left are very reactive

The nonmetals on the right are less active

The elements on the far left of the periodic table are very reactive.

The elements on the far right of the periodic table are the least reactive.

iron

copper

12

Properties of Metals

You have read about metals and may already know some

important things about them Have you ever noticed that most

metals are shiny and can bend without breaking? Refl ectivity

and malleability are properties many metals share All metals

are also solid at room temperature, except for mercury At room

temperature, mercury is a liquid

Metals also share conductive qualities A good conductor is a

material that lets heat and electricity travel through it Metals are

ductile so they can be made into wire These properties make

metals very useful for wiring your home and electrical devices

Many common metals are pure elements Nickel, iron, and

copper are all pure elements

13

Mixed Metals

Many metals are not pure elements When two or more metals are mixed together, a metal alloy results Mixing metals together gives the alloy new and different properties For instance, when carbon and iron mix together, the resulting steel alloy is much stronger than iron alone Brass, another common mixture made from copper and zinc, is less malleable than copper and prettier than zinc

Musical instruments made of metal, such as trumpets, saxophones, and tubas, are often made of brass

Brass is an alloy of copper and zinc

It has different properties than copper and zinc.

14

Compounds

When two or more elements combine, they form a

compound The compound has different properties than

the elements within it For example, water is made up of two

hydrogen atoms and one oxygen atom Both hydrogen and

oxygen are gases that you can’t see, touch, or hold at room

temperature When they combine to form the compound water,

you can pour it, boil it, and freeze it

Remember the letter symbols from the periodic table?

Compounds have formulas that use these symbols The formula

tells how many atoms of each element make up the compound

The formula for water is H2O H is the symbol for hydrogen,

and the 2 tells you how many hydrogen atoms are in the

compound There are no numbers after the O for oxygen, so

there is only one atom of oxygen in the formula Water always

has twice as many hydrogen atoms as oxygen atoms

= oxygen

= hydrogen

= carbon

15

Hydrogen and oxygen can join with other elements to create completely new compounds Oxygen, hydrogen, and carbon join

to make sugar This crystal has little in common with oxygen and hydrogen gas, or the solid carbon found in coal

Elements react differently depending on what they combine with Sodium combined with chlorine reacts to form table salt Sodium combined with water creates a violent reaction of sodium hydroxide and hydrogen gas

Compounds make up much more of the substances on Earth than pure elements A very common substance, water, is a compound that makes up about 60 percent of your body

Oxygen, hydrogen, and carbon combine

to make sugar.

chlorine sodium

16

Salt Compounds

Many compounds form by sharing electrons, but there are

other ways for compounds to form Salts are compounds made

up of particles held together by oppositely charged atoms

Particles with more electrons than protons are negatively

charged Particles with more protons are positively charged

Opposite charges attract and pull the particles together

Most salts share two properties: they are made up of one

metal and one nonmetal element, and they can form crystals

Brittle crystals develop when particles arrange themselves in a

regular pattern Common table salt is just one of many types of

salt that have these properties

Each crystal of salt has

an organized pattern.

17

Salts can form when chemicals called acids and bases combine Hydrochloric acid is a highly dangerous acid When it combines with sodium hydroxide, a dangerous base, they form sodium chloride and water The salt is dissolved in the water, but salt crystals form if the water evaporates When hydrochloric acid or sodium hydroxide is mixed with metals, the result is a violent reaction

Acids and bases can be poisonous and corrosive They can burn your skin It’s important to be very careful while handling chemicals Never put any chemicals near your face

or in your mouth during science experiments Even though sodium chloride is a harmless salt, many salts are actually poisonous

Sodium hydroxide (left) and hydrochloric acid (right) react in violent ways (when combined with magnesium and zinc pieces, respectively).

What can salts do?

Salts, as you already know, are made up of metal and

nonmetal elements They form into a regular pattern of brittle

crystals They are also resistant to melting until they are heated

at a very high temperature Even though salt is resistant to heat,

it dissolves very easily in plain water If you continue to pour

salt into water, it will reach a point where it stops dissolving

When salts dissolve in water, they make the water an excellent

conductor for electricity

Salts dissolve in water

At some point, the salt will no longer dissolve no matter how much you stir.

pure copper sulfur + oxygen copper + copper + chlorine

19

Once elements combine

to form salts, the salt has very different properties than the elements that went into it The photos below show how copper combines with other substances to form salts When copper is combined with sulfur and oxygen, copper forms a blue salt When combined with chlorine,

it forms a green salt Neither of these salts looks like copper, nor can they be made into wire or bent into different shapes They are now brittle crystals

On its own, sodium is a soft metal that reacts explosively with water When combined with the poisonous yellow gas chlorine, the two create the safe little crystals you recognize as table salt