Matter & The Atom. Anything that takes up space and has mass Can be classified as solid, liquid, gas or plasma Matter.

Matter & The Atom

Anything that takes up space and has mass

Can be classified as solid, liquid, gas or plasma

Matter

Is it matter?

What is not matter?

ENERGY, HEAT, LIGHT, ELECTROMAGNETIC WAVES, MAGNETIC FIELDS, IDEAS, ETC.

Properties of MatterDescribe the characteristics and behavior

of matter, including the changes that matter undergoes

Observing Matter Macroscopic Observations: Observations made with the

5 senses

Microscopic Observations: Observations made with a microscope

Submicroscopic Observations: Observations of substances so small they cannot even be seen with a microscope

Macroscopic Microscopic Submicroscopic

Qualitative Observation: Describes the properties of a substance

Quantitative Observation: An observation that involves a numerical value.

Physical Properties

What are the physical properties represented in the image above?

chara

cteris

tic

s

quantitative

qualitative

Chemical Properties

MIXTURESTwo or more elements physically combined.

How can you tell something is a mixture?It can be physically separated into its parts.

Heterogeneous Mixtures

• The prefix “hetero” means “different”• A mixture with different compositions throughout• You can see each phase (part) of the mixture

Homogeneous Mixtures

• The prefix “homo-” means “the same”

• A mixture that is the same throughout

• You cannot see the phases (parts) of the mixture.

HETEROGENEOUS OR

HOMOGENEOUS?

Solutions• Solute: The substance being dissolved in a

solution• Solvent: The substance that dissolves the solute• Aqueous Solution: A solution in which water is

the solvent

What is the solute?What is the solvent?

82% Fe

18% Cr

ALLOY

NAME OF ALLOY % MAKE UP EXAMPLE

Stainless Steel 73-79% Fe14-18% Cr7-9% Ni

Sterling Silver 92.5% Ag7.5% Cu

18-karat white gold 75% Au12.5% Ag12.5% Cu

14 karat gold 58% Au14-28% Ag14-28% Cu

Methods to Separate Mixtures

• Filtration: Separates a solid from a liquid

Separating…

• Magnet: Separates Fe, Co, or Ni

Separating…• Distillation: Separates two or more liquids

with different boiling points.

Separating…• Crystallization: Separates crystalline solids

from a saturated liquid

Separating…

• Chromatography: Separates different types of liquids

PURE SUBSTANCEPURE SUBSTANCE Matter with the same fixed Matter with the same fixed

composition and propertiescomposition and properties– First Type of Pure SubstanceFirst Type of Pure Substance

ElementElement– The Periodic Table:The Periodic Table: A chart that lists the chemical A chart that lists the chemical

name and chemical symbol for each elementname and chemical symbol for each element– Chemical Symbol:Chemical Symbol: A shorthand abbreviation for A shorthand abbreviation for

the name of an elementthe name of an element– You can tell a substance is an element because it You can tell a substance is an element because it

is on the periodic tableis on the periodic table

-Can you separate an element? No-Can you separate an element? No

Aluminum = ___ Aluminum = ___ Gold = ____ Gold = ____ Tin = ____ Tin = ____

PURE SUBSTANCEPURE SUBSTANCE Matter with the same fixed composition and propertiesMatter with the same fixed composition and properties

– Second Type of Pure SubstanceSecond Type of Pure Substance CompoundCompound

– Chemical Formula:Chemical Formula: A combination of chemical A combination of chemical symbols that show what elements make up a symbols that show what elements make up a compound and the number of atoms of each elementcompound and the number of atoms of each element Subscript:Subscript: A number written to the lower right of A number written to the lower right of

an element symbol to indicate the number of an element symbol to indicate the number of atoms of thatatoms of that

– How do you know if a substance is a compound? If it How do you know if a substance is a compound? If it is 1 thing only—and it is not on the periodic table.is 1 thing only—and it is not on the periodic table.

– Can you separate a compound? Yes—by chemically Can you separate a compound? Yes—by chemically decomposing it.decomposing it.

NaHNaH22COCO33 Mg(OH)Mg(OH)22

Decomposing a CompoundDecomposing a Compound

ElectrolysisElectrolysis– ““To tear apart with electricity”To tear apart with electricity”– The process in which electrical energy The process in which electrical energy

causes a non-spontaneous chemical causes a non-spontaneous chemical reaction to occur reaction to occur May break a compound apart into its May break a compound apart into its

elementselements Electrolysis of PbBrElectrolysis of PbBr22 & ZnCl & ZnCl22

Electrolysis of WaterElectrolysis of Water

THE GREEK PHILOSOPHERS

• 250 B.C.• Four Fundamental Elements:

Earth, Wind, Water, and Fire made up everything in the world

DEMOCRITUS

• 450 B.C.• Seashell experiment led to

development of the idea of an indivisible piece of matter called “atomos”•Atom: The building

block of matter

•Problem: No experimental data to back his concept

•Aristotle: Discredited Democritus

DEMOCRITUS’ ATOM

Law of Conservation of Mass•Antoine Lavoisier--1782 (Mercury & Oxygen Experiment)

•Mass cannot be created nor destroyed in a chemical reaction

•The mass of the reactants must equal the mass of the products in a chemical reaction

Law of Definite Proportions

• Joseph Louis Proust-1799

• In a pure compound, the elements combine in definite proportions to one another according to mass– Water is always 2 Hydrogen : 1 Oxygen

Law of Definite Proportions

Malachite

John Dalton-1803

·Elements are made of tiny particles called atoms

·All atoms of a given element are identical

·Atoms of a given element are different then every other element

·Atoms of one element can combine with atoms of another element to form compounds

·Atoms are indivisible and indestructible. Atoms can only be rearranged in chemical reactions--not created, divided, nor destroyed.

DALTON’S ATOM

Benjamin Franklin-1700’s

• Kite experiment:– Objects have 1 of

2 electric charges• Called them + &

-

• Like charges repel

• Opposite charges attract

Michael Faraday--1839

• Suggested that atoms contain particles that have electrical charge– Electricity (elektron, Greek word for amber)

• The flow of electrons in a substance– Static: Stationary

– Static Electricity: Electrical charges not in motion (socks out of a dryer)

J.J. THOMSON--1897

CATHODE RAY TUBE: Evacuated glass tube in which a stream of electrons emitted by a cathode strikes a fluorescent material, causing it to glow

CATHODE: The electrode that brings electrons to the ions or atoms in a solution.

TELEVISIONS ARE CATHODE RAY TUBES

THOMSON’S PLUM-PUDDING MODEL OF THE ATOM

Electron’s (negatively

charged particles) are

embedded in a ball of positive

charge.

Thomson measured the degree to which a magnetic field and an electric field deflected the cathode ray. Since the field was

attracted to the positive charge, he knew it must contain a negative charge. By doing this he discovered the electron.

Henri Becquerel--1896

• Accidentally placed uranium on unexposed photographic film– Found an image had been produced on the film– Discovered that uranium exhibits radioactivity

• Radioactivity is the spontaneous emission of radiation from an element

• Marie & Pierre Curie were awarded the Noble Peace Prize, along with Becquerel, for the discovery of radioactivity

• The Curies isolated two other radioactive elements—radium and polonium

• Elements with atomic numbers greater than 83 are radioactive

Radioactivity

Robert Millikan—1909Oil Drop Experiment

Using this experiment, Millikan determined the charge of the electron

Ernest Rutherford

Alpha particle (α)—a particle with a +2 charge

Beta particles ()—high-speed electrons

Gamma radiation ()—not composed of particles

RUTHERFORD’S GOLD FOIL EXPERIMENT--1911

If Thomson’s model was correct, positive α particles would all go straight through the atom. However, Rutherford’s Gold Foil Experiment proved this to be untrue. Instead, every once in a while the α particle was repelled. Since α particles are positive, that meant there was a small, positive part of the atom.

RUTHERFORD’S NUCLEAR MODEL OF THE ATOM

Concept: The atom is made of mostly empty space, containing electrons, surrounding a small, dense,

positively charged nucleus.

-- Center of the atom -- subatomic

particle with no charge located in the nucleus

-- subatomic particle with a positive charge located in the nucleus

James Chadwick—1930’s

Scanning Tunneling Microscope (STM)

STM IMAGES

Nickel Platinum

Iron on Copper

WHO RECEIVED THE NOBEL PRIZE FOR STM IN 1986?

• Gerd Binnig and Heinrich Rohrer of the IBM Research Laboratory– 1981-Invented the STM which formed images

of individual atoms

ATOM MANIPULATION

Iron on Copper

Carbon Monoxide Man (on

Platinum)

Xenon on Nickel

Particle Accelerator--FermiLab

What’s smaller than a proton?

Other particles: quarks, gluons, mesons, muons & other exotic particles—no immediate chemical

impact

Atoms are

composed of

protons, electrons &

neutrons which

explain the behavior

of matter.

ATOMIC SIZE

A typical atom is 0.000000001 meter across or 1 billionth of a meter

A quark is 0.000000000000000001 meter

ATOMIC SIZE

If the atom was the same size as the distance between the Earth and the Moon then:

-the nucleus would be the length of a golf course

-a proton would be about the size of a football field

-a quark would be about the size of a golf ball

SUBATOMIC PARTICLES

Symbol Charge (relative)

Location

Mass (relative)

Electron

e- -1 Outside nucleus

0 amu

Proton p+ +1 Inside nucleus

1 amu

Neutron

n0 0 Inside nucleus

1 amu

Amu = atomic mass units= 1/12 the mass of a carbon-12 atom

Atomic Number

= # of protons

In an ATOM also= # of _________________

because: an ATOM is electrically neutralso: the positive = the negative

protons electrons

A lithium atom with 3 protons & 3 electrons has no overall charge.

3 protons + 3 electrons =

(+3) + (-3) = 0

A boron atom with 5 protons & 5 electrons has no overall charge.

5 protons + 5 electrons =

(+5) + (-5) = 0

• The atomic number is the number that is always used to identify an element– Each element has a unique # of

protons and the number of protons of a particular element can never change

• The elements are arranged by atomic number on the periodic table

Atomic Number

Example

Element

Name

Element

Symbol

Atomic Numbe

r

# of proton

s

# of electro

ns

10

Ag

62

ISOTOPESIsotopes: Different atoms of the same element with

the same number of protons but a different number of neutrons

• What’s this mean? There are different types of the same element

• Isotopes of the same element are: chemically alike, because they have the same number of protons & electrons

90% of the universe, H2O

D2O (moderator in nuclear reactors to slow down neutrons)

Radioactive, produced in nuclear reactors, fission bombs

Carbon Isotopes

MASS NUMBER

Mass Number: The sum of the isotope’s number of protons and neutrons-The mass number is the mass of just 1 of the element’s isotopes-The mass number is always a whole number

Mass Number = (# of p+) + (# of no)Neutrons =

Mass # must be calculated, it cannot be found on the periodic table!

A P E M A NTOMIC

NUMBER

=

ROTONS

LECTRONS

&

ASS

NUMBER

TOMIC

NUMBER

EUTRONS

= +

Examples

What is the mass number of an atom with 17

protons and 20 neutrons?

How many neutrons does a carbon atom with

a mass number of 14 have?

Isotopic Symbol:Mass #

Atomic #

Naming an Isotope:Element Name-Mass #

ISOTOPES

Symbol

EXAMPLESWrite the isotopic symbols for the element with:21 protons, 24 neutrons

53 protons, 74 neutrons

How many protons, electrons and neutrons are in an atom of 32

15P?

EXAMPLE OF AN ISOTOPE

Isotope Isotopic Symbol

Mass # Atomic # # of Protons

# of Neutrons

Carbon-12

Carbon-13

Atomic Mass Unit: Unit for atomic mass• 1 amu = 1/12 (mass of carbon-12 atom)

= 1.66 x 10-24 g

Atomic Mass: a weighted average of all of the isotopes of an element

• Different from mass number• Is found on the periodic table• the atomic mass value will be closest to the mass

of the isotope that is most abundant

ISOTOPES

To calculate atomic mass:

Atomic Mass = [(% abundance isotope 1) x (mass of isotope 1)] + [(% abundance isotope 2) x (mass of isotope 2) ] + …

Example: Calculate the atomic mass of carbon if carbon-12 has a percent

abundance of 98.89% and carbon-13 has a percent abundance of 1.11%.

ATOMIC MASS