Intro to Chemistry:Intro to Chemistry:Atoms and the Periodic Atoms and the Periodic

TableTable

Unit 7 – Part AUnit 7 – Part A

The Universe is Made of Two The Universe is Made of Two Things:Things:

1.1.Matter (The Matter (The Stuff).Stuff).

2.2.Energy Energy (What moves (What moves the stuff).the stuff).

Chemistry:Chemistry:

ChemistryChemistry is the study of matter and is the study of matter and change.change.

Matter is something that has mass and takes up space, “stuff”

What is Matter Made of?What is Matter Made of?Matter Matter is made up of elements and compounds.

ElementsElements are any material that is made up of are any material that is made up of one single type of atom.one single type of atom. A gold brick – only gold atomsA gold brick – only gold atoms Graphite pencil – only carbon atoms.Graphite pencil – only carbon atoms.

Elements are listed on the Elements are listed on the Periodic TablePeriodic Table

Naming ElementsNaming Elements

Atomic SymbolAtomic Symbol designates each element. designates each element. Comes either from the first letter (1Comes either from the first letter (1stst two letters) two letters)

of the element or from the element’s Latin name.of the element or from the element’s Latin name.Carbon = CCarbon = C

Gold = Au (aurum)Gold = Au (aurum) First letter is always capitalized.First letter is always capitalized.

First direct evidence of atoms was First direct evidence of atoms was discovered by Robert Brown in 1827.discovered by Robert Brown in 1827. Brownian motionBrownian motion

Elements combine with each other

to form compounds

O

H

O

H

HO

H

HO

H

HH

H H

O

Element? Compound? Both?

Ne

Ne

Ne

Ne

Ne

Kr

HH

O

C

O

O

Na

Ne

Cl

Atoms’ Empty SpaceAtoms’ Empty Space

Like charges repel, keeping space in-Like charges repel, keeping space in-between atomsbetween atoms Electrons on the outer shell of the atom Electrons on the outer shell of the atom

produce a charge.produce a charge. Electrical repulsions prevent you from passing Electrical repulsions prevent you from passing

through walls and through your seat.through walls and through your seat.

The Atoms’ Make-upThe Atoms’ Make-upProton – particle found in the atomic Proton – particle found in the atomic nucleus and carries a positive charge.nucleus and carries a positive charge.

Neutron – particle found in the atomic Neutron – particle found in the atomic nucleus and carries no charge.nucleus and carries no charge.

Electron – tiny particle surrounding the Electron – tiny particle surrounding the nucleus and carries a negative charge.nucleus and carries a negative charge.

The Atoms’ Make-upThe Atoms’ Make-up

Atomic numberAtomic number represents the number of represents the number of protonsprotons contained in each atomic nucleus. contained in each atomic nucleus. Elements are listed in order of increasing Elements are listed in order of increasing

atomic numbers.atomic numbers. Hydrogen = H = 1Hydrogen = H = 1 Helium = He = 2Helium = He = 2 Lithium = Li = 3Lithium = Li = 3 Beryllium = Be = 4Beryllium = Be = 4

The Atoms’ Make-upThe Atoms’ Make-upEvery element has a Every element has a definite number of definite number of protons, but the number protons, but the number of neutrons it contains of neutrons it contains may vary.may vary. Atoms of the same Atoms of the same

element that contain element that contain different numbers of different numbers of neutrons are neutrons are isotopesisotopes..

The Atoms’ Make-upThe Atoms’ Make-up

We identify isotopes by their We identify isotopes by their mass mass numbernumber, the total number of protons and , the total number of protons and neutrons they contain.neutrons they contain. Hydrogen isotopes:Hydrogen isotopes:

H-1 = only 1 protonH-1 = only 1 proton

H-2 = 1 proton and 1 neutronH-2 = 1 proton and 1 neutron

H-3 = 1 proton and 2 neutronsH-3 = 1 proton and 2 neutrons

Atomic massAtomic mass represents the sum of the represents the sum of the masses of all the atom’s components.masses of all the atom’s components.

How Does Matter Change?How Does Matter Change?

Does matter always

stay the same?

Matter Doesn’t Always Stay The Matter Doesn’t Always Stay The Same:Same:

How Does Matter Change?How Does Matter Change?

1.Physical change:

OH

moves atoms or compounds around, but doesn’t break or make any bonds between atoms

H

OHH

OHH

OHH

How would you be able to tell a physical change happened?

- may change shape, size, or phase (solid, liquid, or gas)

- Usually easy to undo

2. Chemical change:

O

H

O

H

H O

HHO

H

Makes and/or breaks bonds between atoms

How would you be able to tell a chemical change happened?

- may change color, change smell, release or absorb energy, or release a gas

- substance turns into something else (difficult to undo)

- aka, a chemical reaction

Physical or Chemical change?

Ne

C

O

O

OO

C

Ne

Ne Ne

NeNe

Ne

Ne

Physical or Chemical change?

Baking soda is added to vinegar

Sugar is added to water

Physical or Chemical change?

Water in the cracks of a rock freezes, breaking the bedrock

Acids in the “roots” of a lichen growing on a rock slowly dissolve the rock over time

Elements Organized by Their Elements Organized by Their PropertiesProperties

Elements Organized by Their Elements Organized by Their PropertiesProperties

Metals: shiny, opaque, and good Metals: shiny, opaque, and good conductors of electricity and heat.conductors of electricity and heat. Malleable and ductileMalleable and ductile Most are solid at room temperature.Most are solid at room temperature.

Elements Organized by Their Elements Organized by Their PropertiesProperties

Nonmetals: poor conductors of electricity Nonmetals: poor conductors of electricity and heat, and may also be transparent.and heat, and may also be transparent. Solid nonmetals are neither malleable nor Solid nonmetals are neither malleable nor

ductile.ductile.

Elements Organized by Their Elements Organized by Their PropertiesProperties

Metalloids: have both metallic and Metalloids: have both metallic and nonmetallic characteristics.nonmetallic characteristics. Boron, Silicon, Germanium, Arsenic, Tin, and Boron, Silicon, Germanium, Arsenic, Tin, and

Antimony.Antimony.

Period and Group OrganizationPeriod and Group Organization

Period and Group OrganizationPeriod and Group Organization

PeriodsPeriods are horizontal rows in the periodic are horizontal rows in the periodic table. (7 total)table. (7 total)

GroupsGroups are vertical columns in the are vertical columns in the periodic table. (18 total)periodic table. (18 total)

Elements in the periodic table gradually Elements in the periodic table gradually change and is called a change and is called a periodic trendperiodic trend..

Identify & Define GroupsIdentify & Define Groups

You and your group will select one of the You and your group will select one of the following groups and collect information:following groups and collect information: Alkaline Metals, Alkaline-Earth Metals, Alkaline Metals, Alkaline-Earth Metals,

Transition Metals, Inner Transition Metals, Transition Metals, Inner Transition Metals, Chalcogens, Halogens, & Noble Gases.Chalcogens, Halogens, & Noble Gases.

Develop a two (2) minute presentation to Develop a two (2) minute presentation to define, give examples, and give important define, give examples, and give important information to the class about your group. information to the class about your group.

Identify & Define GroupsIdentify & Define Groups

Alkaline Metals:Alkaline Metals: Group 1 elements, history links properties for Group 1 elements, history links properties for

the preparation of soaps.the preparation of soaps. Lithium, Sodium, & Potassium.Lithium, Sodium, & Potassium.

Alkaline-Earth Metals:Alkaline-Earth Metals: Group 2 elements, do not melt or change Group 2 elements, do not melt or change

when placed in fire, “fire-resistant”.when placed in fire, “fire-resistant”. Magnesium, Calcium, & Strontium.Magnesium, Calcium, & Strontium.

Identify & Define GroupsIdentify & Define Groups

Transition Metals:Transition Metals: Group 3-12 elements, do not form alkaline Group 3-12 elements, do not form alkaline

metals and tend to be harder and used for metals and tend to be harder and used for structural purposes.structural purposes.

Iron, Copper, Nickel, Silver, & Gold.Iron, Copper, Nickel, Silver, & Gold.

Inner Transition Metals:Inner Transition Metals: In the 6In the 6thth and 7 and 7thth element groups. element groups. Lanthanides (associated with LED screens)Lanthanides (associated with LED screens) Actinide (Uranium & Plutonium)Actinide (Uranium & Plutonium)

Identify & Define GroupsIdentify & Define Groups

Chalcogens:Chalcogens: Group 16 elements, derived from the term Group 16 elements, derived from the term

“ore-forming”.“ore-forming”. Oxygen & Sulfur.Oxygen & Sulfur.

Halogens:Halogens: Group 17 elements, derived from the term Group 17 elements, derived from the term

“salt-forming” and associated with cleaning.“salt-forming” and associated with cleaning. Chlorine, Bromine, & Iodine.Chlorine, Bromine, & Iodine.

Identify & Define Groups:Identify & Define Groups:

Noble Gases:Noble Gases: Group 18 elements, all unreactive gases that Group 18 elements, all unreactive gases that

tend not to combine with other elements.tend not to combine with other elements. Helium, Neon, Argon, & Xenon.Helium, Neon, Argon, & Xenon.

What is an Atom?What is an Atom?

What in the world is the world made of??

Atom - the basic unit of matter

- the smallest particle

Just how small are they?

Video: Just how small is an atom?Video: Just how small is an atom?

Are atoms the smallest thing?

Subatomic particles - the parts inside an atom

The 3 Subatomic particles:

+

-

Name Charge Mass (a.m.u.)

Location

Proton + 1 In the nucleus

Neutron 0 1 In the nucleus

Electron — Almost zero

Outside the nucleus in

orbitals

amu = atomic mass unit