The Nature of Matter 1 12/6/16 Matter & Energy Matter - - PDF document

12/6/16 1

The Nature of Matter

12/6/16 2

Matter & Energy Matter

• Matter is the "stuff" of the universe.
• Matter is anything that occupies space and has mass.
• Matter exists as a solid, liquid, gas, and plasma.
• Matter may be changed both physically and chemically.
• The Law of Conservation of Matter states that matter

cannot be created or destroyed, only changed.

12/6/16 3

Energy

• Energy has no mass, does not take up space, and can
• nly be measured by its effects on matter.
• Energy is commonly defined as the ability to do work or

to put matter into motion.

• When energy is actually doing work, it is referred to as

kinetic energy.

• When energy is inactive or stored, it is called potential

energy.

• All forms of energy exhibit both kinetic and potential

work capacities.

Forms of Energy

12/6/16 4

Chemical Energy

• Chemical energy is the

energy stored in the bonds

• f chemical substances.
• When the bonds are broken

the stored potential energy is released for use.

• It becomes kinetic energy,
• r energy in action that

causes an effect on matter.

Electrical Energy

• Electrical energy is energy

that results from the movement of charged particles.

• In your body, an electrical

current is generated when charged particles, called ions, move across cell membranes.

12/6/16 5

Mechanical Energy

• Mechanical energy is

directly involved in moving matter.

• As the muscles in your legs

shorten, they pull on your bones, causing your limbs to move.

Radiant Energy

• Radiant energy is energy that travels in waves.
• It is the energy of the electromagnetic spectrum, which

includes X rays and infrared, light, radio, and ultraviolet waves.

12/6/16 6

Atoms Atoms

• Matter consist of atoms.
• An atom is the smallest unit of matter that has the

chemical properties of that element.

• Atoms cannot be broken down into smaller particles.

12/6/16 7

The Structure of an Atom

• Atoms are made up of small parts called protons,

electrons, and neutrons.

• Protons are particles that have a positive (+) electrical

charge.

• Neutrons are particles that are neutral (o), they have no

charge.

• Electrons are particles that have a negative (-) electrical

charge.

The Nucleus of an Atom

• The protons and neutrons of an atom are packed close to
• ne another and form the nucleus.
• The nucleus has a positive charge because protons have a

positive charge and neutrons have no charge.

• The nucleus makes up most of an atom’s mass.

12/6/16 8

Electrons

• The electrons of an atom move in a certain area of space

called an electron cloud that surrounds the nucleus.

• Because opposite charges attract each other, the

negatively charged electrons are attracted to the positively charged nucleus.

• This attraction is what holds electrons in the atom.

Structure of Atoms

12/6/16 9

Atomic Mass

• The total number of protons and neutrons in an atom is its

atomic mass.

• Electrons have much less mass than protons and

neutrons.

• It would take 1,840 electrons to equal the mass of one

proton.

Atomic Number

• The number of protons in the nucleus of an atom is called

the atomic number.

• All elements have their own atomic number.
• Since atoms have to have an equal number of protons and

electrons, the atomic number is also equal to the number

• f electrons in an atom.

12/6/16 10

Atomic Numbers & Masses

• Atomic Number = the number of protons or the number of

electrons.

• Atomic Mass = the number of protons and neutrons.

Isotopes

• An atom that has more neutrons than protons is called an

isotope.

• Isotopes of the same element will have slightly more mass

because of the different numbers of neutrons.

12/6/16 11

Radioactive Isotopes

• Some isotopes are radioactive, meaning that their nuclei

are unstable and break down at a constant rate over time.

• Radioactive isotopes have a number of important scientific

and practical uses.

• In medicine radioactive isotopes are used as tracers so

doctors can view the path of a substance through the body.

• Geologists determine the ages of rocks and fossils by

analyzing the isotopes found in them.

Electron Energy Levels

• The electrons occupy a specific space around the nucleus
• f an atom.
• This space is called energy levels, energy shells, and

electron shells.

• An atom’s chemical properties are determined by the

number of the electrons in the energy level furthest away from the nucleus.

• There are 7 energy levels and each level can hold a

certain number of electrons.

12/6/16 12

• Energy Level 1 is the

closest to the nucleus and can only hold 2 electrons.

• Energy Level 2 can hold a

maximum of 8 electrons.

• Energy Level 3 can hold up

to 18 electrons.

• All the other energy levels

hold larger and larger numbers of electrons.

Energy Levels Elements

• An element is a substance that cannot be broken down

into simpler substances by chemical means.

• Each element has physical and chemical properties that

can be used to identify it.

• Of the 118 elements that have been identified,

approximately 98 elements occur naturally on Earth.

• Eight of these 98 elements make up more than 98% of

Earth’s crust.

• To classify the elements the Periodic Table is used.

12/6/16 13

Periodic Table

• Elements on the periodic table are arranged according to

their atomic numbers.

• Elements in the same column on the periodic table have

similar arrangements of electrons in their atoms.

• Elements that have similar arrangements of electrons have

similar chemical properties.

12/6/16 14

How It’s Organized

• The periodic table is organized like a big grid.
• The elements are placed in specific places because of the

way they look and act.

• In the Periodic Table, there are Periods (left to right)

and Groups (up and down).

• Each Period and each Group means something different.

Groups & Periods

12/6/16 15

Groups

• The elements in a GROUP have the same number of

electrons in their outer energy level.

• Every element in the first column (Group #1) has one

electron in its outer energy level.

• Every element on the second column (Group #2) has two

electrons in the outer energy level.

• Each row (left to right) is called a PERIOD.
• Elements that are in the same Period have the same

number of energy levels.

Periods

12/6/16 16

Families

• Scientists group families of elements by their

chemical properties and how the elements react with the outside world.

• Alkaline Metals
• Alkaline Earth Metals
• Transition Elements
• Halogens
• Inert Gasses

Metals

• Almost 75% of all elements are classified as metals.
• Any substance with high electrical conductivity, luster,

and malleability, and easily loses electrons to form positive ions.

• Metals are also defined by their position on the Periodic

Table

• These groups include alkaline metals, alkaline earth

metals, transition metals, and rare earth metals.

12/6/16 17

Alkalaline Metals

• Alkaline metals are found in

Group 1 (excluding hydrogen).

• These elements are very

reactive.

• They all have one electron in

their outer energy level.

• That's one electron away from

being stable.

• Examples include lithium,

sodium, potassium, and rubidium.

Alkalaline Earth Metals

• Alkaline earth metals are found

in Group 2.

• These elements are somewhat

reactive.

• They all have two electrons in

their outer energy level.

• That's two electrons away from

being stable.

• Examples include beryllium,

magnesium, calcium, and strontium.

12/6/16 18

Transition Elements

• Transition metals are able to

put more than eight electrons in the energy level that is one in from the

• utermost one.
• Examples include silver,

gold, copper, nickel, zinc, and platinum.

Halogens

• The halogen family is Group 7
• n the periodic table.
• Halogens are all just one

electron shy of having full energy levels.

• Because they are so close to

being stable, they will combine with many different elements.

• They will often bond with

metals.

• Examples include fluorine,

chlorine, bromine and iodine.

12/6/16 19

Inert Gasses

• All of the inert gases have

full outer energy levels with eight electrons.

• They are all in Group 8 and

they will not react with any

• ther element.
• Examples include helium,

neon, argon, and krypton.

Compounds and Bonds

12/6/16 20

Chemical Compounds

• In nature, most elements are found combined with other

elements in compounds.

• A chemical compound is a substance formed by the

chemical combination of two or more elements in definite proportions.

• Scientists show the composition of compounds by a kind
• f shorthand known as a chemical formula.
• Water (dihydrogen monoxide), which contains two atoms
• f hydrogen for each atom of oxygen, has the chemical

formula H2O.

Chemical Compounds

• The formula for table salt is NaCl.
• This indicates that the elements - sodium and chlorine -

combine in a 1:1 ratio.

• Sodium is a silver-colored metal that is soft enough to

cut with a knife and reacts explosively with cold water.

• Chlorine is a very poisonous, greenish gas.
• Sodium and chlorine combine to form sodium chloride

(NaCl), or table salt.

• Sodium chloride is a white solid that dissolves easily in

water.

12/6/16 21

Chemical Compounds

Sodium Chlorine Salt + =

Ions

• Atoms are generally neutral, they do not have an electrical

charge.

• Sometimes electrons move from one atom to another.
• When an electron moves from one atom to another, both

atoms become electrically charged.

• That means that they will become either positive (+), or

negative (-).

• An atom that has an electrical charge is called an ion.

12/6/16 22

Ions

• Sodium atoms have 11 electrons.

– 2 electrons in the first energy level – 8 in the second energy level – 1 in the third energy level

• The electron in the third level is usually given up. Sodium can’t

hold on to it.

• Since there are more protons than electrons, sodium has a

positive (+) charge.

Ions

12/6/16 23

Ions

• A chlorine atom has a total of 17 electrons.

– 2 in the first level – 8 in the second level – 7 in the third level

• Chlorine usually attracts an electron to it.
• Since there are more electrons than protons, chlorine has

a negative (-) charge.

Ions

12/6/16 24

Ions

• Sodium and chlorine, two very unstable elements, will

combine to form salt, sodium chloride.

Ionic Bonds

• A bond that results in the transfer of electrons from one

atom to another is called an ionic bond.

• A compound that forms through the transfer of electrons

is called an ionic compound.

• Sodium chloride (NaCl), common table salt, is an ionic

compound.

12/6/16 25

Ionic Bonds Covalent Bonds

• Electrons do not have to be completely lost or gained for

atoms to become stable.

• Electrons can be shared in such a way that each atom is

able to fill its outer energy level part of the time.

• Molecules in which atoms share electrons are called

covalent bonds.

12/6/16 26

Covalent Bonds Hydrogen Bonds

Hydrogen bonds are extremely weak bonds formed when a hydrogen atom bound to one electron-hungry nitrogen

• r oxygen atom is

attracted by another electron-hungry atom, and the hydrogen atom forms a "bridge" between them.

12/6/16 27

Mixtures, Solutions & Suspensions Mixtures

• On Earth, elements and compounds are generally mixed

together.

• A mixture is a combination of two or more substances that

are not chemically combined.

• The substances that make up a mixture keep their

individual properties.

• Unlike a compound, a mixture can be separated into its

parts by physical means.

• There are two kinds of mixtures: heterogeneous mixtures

and solutions.

12/6/16 28

Heterogeneous Mixtures

• Mixtures in which two or more substances are not

uniformly mixed are called heterogeneous mixtures.

• For example, granite is a heterogeneous mixture of

crystals of the minerals quartz, feldspar, hornblende, and biotite.

Solutions

• Two types of mixtures that can be made with water are

solutions and suspensions.

12/6/16 29

Solutions

• A solution is a mixture of two or more substances that are

uniformly spread-out throughout the mixture.

• A solution has two parts; the part that does the dissolving

and the part that is dissolved.

• The liquid that does the dissolving is called the solvent.
• The substance that is dissolved is called the solute.

Suspensions

• Some materials do not dissolve when placed in water but

separate into pieces so small that they do not settle out.

• The movement of water molecules keeps the small

particles suspended.

• Such mixtures of water and non-dissolved material are

known as suspensions.

• Some of the most important biological fluids are both

solutions and suspensions.

12/6/16 30

Acids, Bases, and pH Acids

• Acids have a sour taste, and can dissolve many

metals.

• Acids will release hydrogen ions (H+) when they

dissolve in water.

• The larger the amount of hydrogen that is

released, the stronger the acid.

12/6/16 31

Bases

• Bases have a bitter taste, and feel slippery.
• When bases are dissolved in water they release

an molecule called hydroxide (OH-).

• The more hydroxide molecules released, the

stronger the base.

The pH Scale

• To measure the strength of an acid or a base,

the pH Scale is used.

• The pH scale goes from 0 to 14 and each

successive change of 1 pH unit represents a 10x change in ion concentration.

12/6/16 32

The pH Scale

• The mid-point of the pH Scale is 7.0.
• A pH of 7.0 means that the liquid is neutral; it is

not an acid or a base.

• Solutions with a pH between 0-6.9 are acidic.
• Solutions with a pH between 7.1 and 14.0 are

basic, or alkaline.

The pH of Common Liquids

12/6/16 33

Chemical Reactions Chemical Reactions

• A chemical reaction is a process that changes one set of

chemicals into another set.

• An important scientific principle is that mass and energy

are conserved during chemical transformations.

• This is also true for chemical reactions that occur in

living organisms.

• Some chemical reactions occur slowly, such as the

combination of iron and oxygen to form rust.

12/6/16 34

Chemical Reactions

• Other reactions occur quickly.
• The elements or compounds that enter into a chemical

reaction are known as reactants.

• The elements or compounds produced by a chemical

reaction are known as products.

• Chemical reactions always involve changes in the

chemical bonds that join atoms in compounds.

Chemical Reactions

• Chemical reactions involve interactions between atoms

and molecules that involve the formation or breaking of chemical bonds.

• Three basic types of chemical reactions are:

– Synthesis reactions – Decomposition reactions – Exchange reactions

12/6/16 35

Synthesis Reactions

• In synthesis reactions, two or more substances called

reactants combine to form a different more complex substance called a product.

• Synthesis reactions result in the formation of new bonds,

and energy is required for the reaction to occur and the new product to form.

• Many such reactions occur in the body in tissue repair.
• Another example is photosynthesis.
• Example: 6CO2 + 6H2O C6H12O6 + 6O2

Decomposition Reactions

• Decomposition reactions result in breakdown of a

complex substance into two or more simpler substances.

• In this type of reaction, chemical bonds are broken and

energy is released.

• Energy can be released in the form of heat, or it can be

captured for storage and future use.

• Decomposition reactions occur when a complex nutrient

is broken down in a cell to release energy for other cellular functions.

• Example: NaCl

Na+ + Cl-

12/6/16 36

Exchange Reactions

• An exchange reaction occurs when two different

reactants exchange parts and form two new products.

• Exchange reactions break down or decompose two

compounds and, in exchange, synthesize two new compounds.

• Certain exchange reactions take place in the blood.
• Example: HCl + NaOH

NaCl + H2O