Lesson 3 Chem

Atomos - Indivisible

Cut a substance over and over where it is no longer dividable. But you still keep the same substance

Antoine Lavoiseier - Law of Conservation of mass

In chemical reactions, Matter is neither created or destroyed

Ex-

4.0 G of Hydrogen + 34.0 G of Oxygen = 36.0 G of Water

Atomic Theory

Elements are made of tiny, Invisible particles called atoms

Atoms of each element are unique

Atoms can join-together in whole number ratios to create compounds

They remain unchanged in chemical reaction

Three Foundational Ideas

1. All matter is composed of atoms

2. Atoms of each element have a unique characteristics and properties

3. In chemical reactions, atoms are not changed, but combine in whole number ratios to form compounds

1860 - Mendeleev

Arranged elements into collumns

• Flourine

• Chlorine

• Bromine

• Iodine

Discovered

• Gallium

Rows of a periodic table are called

Periods

Columns of a periodic table are called

Groups (Families)

Periodic table uses what form of elements to label

One to Two letter abbreviations

Main group columns

1A - 8A

Transition Metals

3 → 12

Are Hard and less reactive

Usually are seen as common building materials

Inner Transition

Lanthanide - Heavier naturally occurring metals called rare earth metals

Actinide - Common naturally occurring elements before uranium

Non-Metals are located at the

Top right and Top left of the periodic table

Metalloids

Between metals and non-metals

Stair-step pattern

Silicone - Seen and used in modern electronics

Alkali Metals

Soft Metals

React violently to water or melt

Alkaline Earth Metals

React slowly with water

Burn brighter (combined with oxygens)

Halogens

Diatomic molecules in elemental form

React quickly with metals and non metals

Form many different compounds

Group 8A - Noble Gasses

Generally don’t form compounds

Gases at room temperature

Early 1800s John Dalton

Stated:

• Atoms of each element are unique

• Atoms combine in whole-number ratios to form compounds

• Atoms are not created or destroyed in chemical reactions

• Subatomic particles - Define identity and behavior of atoms

Subatomic particles use two distinct categories to describe particles

• Mass & Charge

• Atomic mass unit (u)

• 1 u = 1.66 × 10^-27 kg

• Ex. Hydrogen atom = 1.0 u

• Charge -

• Opposite charges attract to each other

• Like charges repel

(Year chemistry changed) 1800s Scientist Alessandra Volta invents an

Electrochemical Cell (battery) - Device capable of moving electrically charged particles

Many scientist used it to discover new elements - especially Mendeleev

1897 Scientist JJ Thomson discovers

The electron - A tiny negatively charged particle

Plum pudding model:

Envisioned negative electrons spread throughout a positively charged material

-Blue berry through a muffin

Ernest Rutherford 1909

Named the Bohr Model - ElectronsOrbit 1913

Tested positvely charged particles called alpha particles

Concludes atoms are mostly empty space, with a dense nucleus at the center (plum pudding model becomes obsolete)

Because of the particle test some particles are pictured to have bounced or reflect off of the atom’s nucleus

The Atom diagram will disclose that all Proton, Neutron, and Electron are a charge and mass of?

• Proton | Mass - 1.0073 u | +1

• Neutron | Mass - 1.0087 u | 0 or —

• Electron | Mass - 0.0005 u | -1

Number of protons determine

The identity of an atom

Atomic Number

Integer value of the number of protons in an atom.

Also tells the number of electrons in a neutral atom

Mass Number

Number of protons + Neutrons

Isotopes

Have the same atomic number, but a different mass number

Writing Atomic Symbol

Mass number is = Proton + Neutron

Atomic number = Protons

Mass # is top left while Atomic # is bottom left

Quantum Model 1920s by Erwin Schrodinger

Electrons behave both as particle and waves

Ion

An atom or overall atom with an overall charge

Nuclear Chemistry

Describe changes that involve nucleus of an atom

Nucleons

Particles in a nucleus - protons and neutrons

Nuclide

An atom or nucleus containing a particular number of protons and neutron

Isotopes

Have the same atomic numbers but different mass number

Nuclear Reaction

Changes in structure of nucleus

Nuclear Equations

Show nuclear changes

(Gains or loses and atomic particle)

Colliding a-

proton into 1v1P (Proton) + 111v48Cd → 111v49 Id + 1v0n (Neutron)

Radioactivity

Spontaneously release of particles and /or energy (radiation) from nucleus

Energy released by this is called radiation

1897 Antoine Becquerel

Initially discovered radiation when placing uranium near substances like sulfide. It would glow

1902 Marie and Pierre Curie

Isolated many radioactive substances

Discover - Radium and Polonium

Identified 3 radioactive decays

• Alpha

• Beta

• Gamma

Alpha Decay

Nucleus ejects an alpha particle - 2 protons and 2 neutrons

Mass number is decreased by 4

Atomic number decrease by 2

Beta Decay (

Neutron decays into two particles - 1 proton 1 electron

Electron is ejected

When larger nucleus exhibit a beta decay the electron exits the nucleus yet proton remains

Atomic number increases by 1 but mass number remains the same

Gamma Decay

Nucleus Releases energy in waves called Gamma Rays

Neither atomic or mass number changes

Nuclear particle adjusting arrangement for stable isotope

Decays happen through a series aka (Decay chain or series)

Half Life

The amount of time required for one-half of a sample of radioactive substance to decay into something else or other substance

Health and Effects of radiation exposure

The three types of radiation have different means of protection against:

• Alpha - Can damage body tissue but can be blocked with Clothes, Sheet of paper

• Beta - Fast moving electrons that can penetrate through clothes Thing sheet metal, and or hard substance can block beta

• Gamma - hardest to block - Heavy lead shield block it

Geiger Counter

Measure the number of radioactive strikes in a given time frame

Measuring Radiation

Geiger Counter

Scintillation Counter - Uses material that produces a tiny flash of light when exposed to radiation strike

Semiconductor Counter - measure different energies from radiation absorbed

Dosimeter - Measures human exposure to radiation

Common Exposure Levels

becquerel (Bq) - the number of decays that occur each second - doesnt indicate effects on humans

Sievert (Sv) - Used to measure impact of radiation on animal tissue - 1Sv = 1 J/kg

rem - 1 Sv = 100 rem (similar to Sievert)

Depends on biological tissue exposed to determine total effective dose

Radiation Imaging

Patient is admistered a dosage of a compound containing a radioactive nuclide.

Emits gamma radiation when in body

Used to locate internal infections

(White blood cells tagged an produce a gamma ray beacon to locate or signal the location of infection)

Radiation Therapy

Commonly used to treat cancer

Used destructive property of rads to destroy cancer cells

Battle rad sickness through process

Use of Geology and Archaeology are a

Clock defining radioactive nuclei and for understanding Earth’s history