Nature of matter ppt

The Nature of Matter, Minerals, and the Periodic Table

Nature of Matter

•Matter = Anything that has mass and volume.

(Mass is the quantity of matter in an object; volume is the amount of space matter takes up.)

What is the difference between mass and weight???

Physical Properties of MatterPhysical Properties of Matter

• Some physical properties describe a particular object:– Iron Nail: Pointy-ended cylinder (shape); made

of a dull, gray-colored solid (color & state ofmatter).

• Some physical properties can be measured: Nail is 2 inches (length), 1 gram (mass).

Any characteristic of matter that you can observe and measure without changing the substances that make up the matter.

Physical Properties (cont.)Physical Properties (cont.)

Examples of physical properties: Examples of physical properties: CCOOLLOORR, , SSIIZZEE, density, odor, volume, temperature, , density, odor, volume, temperature, melting point & boiling point.melting point & boiling point.

Every substance has physical properties Every substance has physical properties that distinguish it from other substances.that distinguish it from other substances.– ExampleExample: The substance IRON is attracted by : The substance IRON is attracted by

a magnet.a magnet.

Separating MixturesSeparating Mixtures A A mixturemixture is a combination that can be is a combination that can be

separated physically.separated physically.

The difference in a physical property can be The difference in a physical property can be used to separate substances in a mixture.used to separate substances in a mixture.

How could you separate a mixture of cocoa How could you separate a mixture of cocoa pebbles cereal and lucky charms?pebbles cereal and lucky charms?Mechanically – boring, but possibleMechanically – boring, but possible

How would you separate a mixture of iron How would you separate a mixture of iron filings and sand?filings and sand? Use aUse a magnet magnet – it will attract the iron filings and – it will attract the iron filings and

leave the sand behind.leave the sand behind.

Physical ChangesPhysical Changes

• If you break a piece of chalk, it loses its original If you break a piece of chalk, it loses its original size and shape (you’ve changed its physical size and shape (you’ve changed its physical properties). properties). BUT…BUT… you have not changed the you have not changed the substances that make up the chalk.substances that make up the chalk.

• Changes of state are examples of physical Changes of state are examples of physical changes – when water freezes, boils, evaporates, changes – when water freezes, boils, evaporates, etc. (The state changes, but not the identity of the etc. (The state changes, but not the identity of the compound.)compound.)

• A change in size, shape, color or state of matter.

• Physical changes do not change the substances in a material.

Chemical ChangesChemical Changes

There are many signs that can tell you when a There are many signs that can tell you when a chemical change has taken place:chemical change has taken place:

Foaming of an antacid tabletFoaming of an antacid tablet Smell in the airSmell in the air Production of energy/heat (exploding firecracker)Production of energy/heat (exploding firecracker)

Burning and rusting are chemical Burning and rusting are chemical changes because different changes because different substances are produced.substances are produced.

• A change of one substance in a material to a different substance is a chemical change.

Solids… Every solid has a definite shape and a definite volume! The molecules in a solid are held very close together. In elements- each element or mineral has a specific

crystal shape. This crystalline shape determines properties for the

element or mineral

Liquids…• A liquid does not have a definite shape, but does have a

definite volume!• The molecules in a liquid are not held as closely

together, so they can “slide” past each other.

Gases…• Gases don’t have a definite shape or volume – they

expand or contract to fill the space available to them.• The molecules in a gas are spread very far apart and can

move in any direction.

ElementsElements

All matter is made up of All matter is made up of ATOMSATOMS (an atom is the (an atom is the smallest particle of an smallest particle of an element).element).

ELEMENTELEMENT - When all the - When all the atoms in a sample of matter atoms in a sample of matter are the same.are the same.

ExamplesExamples: Carbon in a : Carbon in a pencil point (C), Oxygen in pencil point (C), Oxygen in air (O) and copper in a air (O) and copper in a penny (Cu).penny (Cu).

Cu OC• In total, there are 109 Elements.

CompoundsCompounds CompoundsCompounds:: Made from atoms of two Made from atoms of two

or more elements that are combined or more elements that are combined chemicallychemically..

Compounds can only be separated Compounds can only be separated through through chemicalchemical means! means!

Ex. NaCl- is table salt, but Ex. NaCl- is table salt, but separately:separately:

ExamplesExamples:: Water – made from the Water – made from the elements hydrogen and oxygen. Sugar elements hydrogen and oxygen. Sugar – made from the elements carbon, – made from the elements carbon, hydrogen and oxygen.hydrogen and oxygen.

A A moleculemolecule is the smallest particle of a is the smallest particle of a compoundcompound..

Matter and Atoms• Atoms are the basic building blocks

of matter.• Atoms have a positively charged

center = nucleus.• The nucleus contains protons and

neutrons.• All around the nucleus there are

negatively charged particles = electrons.

• The mass of the electrons is much smaller than the mass of the protons and neutrons. Thus, most of the mass in an atom is located in the nucleus.

Protons, Neutrons & Protons, Neutrons & Electrons!Electrons!

A neutron is A neutron is neutralneutral; a proton is ; a proton is positivepositivelyly charged, and an electron is charged, and an electron is negativenegativelyly charged. charged.– The nucleus is positively charged – why???The nucleus is positively charged – why???

Comparison Of Particles In An AtomComparison Of Particles In An AtomParticlesParticles Relative MassRelative Mass ChargeCharge Location in AtomLocation in Atom

ProtonProton 11 +1+1 Part of nucleusPart of nucleus

NeutronNeutron 11 00 Part of nucleusPart of nucleus

ElectronElectron 00 -1-1 Moves around Moves around nucleusnucleus

Atomic NumberAtomic Number

The The atomic numberatomic number of an atom is the number of protons of an atom is the number of protons in its nucleus.in its nucleus. Example: Every carbon atom has 6 protons. This means its Example: Every carbon atom has 6 protons. This means its

atomic number is 6 also!atomic number is 6 also!

The number of electrons in an atom is The number of electrons in an atom is equalequal to the to the number of protons.number of protons. How many electrons does carbon have???How many electrons does carbon have???

An atom is electrically An atom is electrically NEUTRALNEUTRAL because it has the because it has the same number of protons and electrons.same number of protons and electrons.

Atomic NumberAtomic Number

Carbon –AtomicNumber is 6, which means it has 6 protons and also 6 electrons!

Every atom of the same element has the Every atom of the same element has the same same number of protonsnumber of protons..

Atoms of different elements have different Atoms of different elements have different numbers of protons – the periodic table is numbers of protons – the periodic table is organized by increasing number of protons organized by increasing number of protons ((increasing atomic numberincreasing atomic number).).

Mass NumberMass Number

• Number of protons and neutrons in an atom.• Mass Number = Protons + Neutrons• Number of Neutrons = (Mass Number) – (Atomic

Number)

• Sodium (Na) has 11 Protons and 12 Neutrons – What is its Mass Number?

• Mass number of Na = 11 + 12 = 23

Atomic Number & Mass NumberAtomic Number & Mass Number

Mass Number(Protons + Neutrons)

Atomic Number(# of Protons and Electrons)

• Na has 11 Protons, 11 Electrons, and 12 Neutrons.

Problem #1…Problem #1…

Which element does He stand for?Which element does He stand for? Helium!Helium!

How many protons does He have?How many protons does He have? Two!Two!

How many electrons does He have?How many electrons does He have? Two!Two!

How many neutrons does He have?How many neutrons does He have? Two! (Mass number - Atomic number = 4 - 2 = 2)Two! (Mass number - Atomic number = 4 - 2 = 2)

Problem #2…Problem #2…

Which element does C stand for?Which element does C stand for? Carbon!Carbon!

How many protons does C have?How many protons does C have? Six!Six!

How many electrons does C have?How many electrons does C have? Six!Six!

How many neutrons does C have?How many neutrons does C have? Six! (Mass number - Atomic number = 12 - 6 = 6)Six! (Mass number - Atomic number = 12 - 6 = 6)

Models of the AtomModels of the Atom

A good model helps us understand A good model helps us understand something we cannot see – the something we cannot see – the atomatom!!

A good model must explain all of the A good model must explain all of the information we have about the atom – as information we have about the atom – as our information changes so must our our information changes so must our models.models.

Niels Bohr created one of the earliest Niels Bohr created one of the earliest models of the atom (1913).models of the atom (1913).

Bohr Model of the AtomBohr Model of the Atom

Bohr’s model had a central nucleus with Bohr’s model had a central nucleus with electrons moving around it in defined electrons moving around it in defined paths or orbits.paths or orbits.

Why would this model also be called the Why would this model also be called the Planetary ModelPlanetary Model of the Atom? of the Atom?

Electron Cloud Model of the AtomElectron Cloud Model of the Atom

Improved Bohr’s model (1926).Improved Bohr’s model (1926).In this model, electron’s move In this model, electron’s move around in an area called the around in an area called the electron electron cloudcloud. It shows the region where an . It shows the region where an electron is electron is likely to belikely to be (it is (it is impossible to determine an exact impossible to determine an exact location).location).Electrons are more likely to be Electrons are more likely to be closer to the nucleus than far away – closer to the nucleus than far away – this explains why the cloud is denser this explains why the cloud is denser near the middle!near the middle!