Basic ChemistryCHAPTER 2-2

Radioisotopes

Heavier isotopes that are unstable and tend to decompose to become more stable

Radioactivity

Radioactivity—process of spontaneous atomic decay

What can we use this for?

Radioactivity

But how does this happen?

Radioactivity

But how does this happen?

nuclei are unstable so dissipate excess energy by emitting radiation in alpha, beta, or gamma rays

Radioactivity

Radiometric Dating:

Uranium 238U to 206Pb, with a half-life of

4.47 billion years 235U to 207Pb, with a half-life of

704 million years.

Carbon Carbon-14 is a radioactive

isotope of carbon, with a half-life of 5,730 years

Very short compared to other isotopes

Radioactivity

PhET Simulation

https://phet.colorado.edu/en/simulation/beta-decay

Inert Elements

Atoms are stable (inert) when the outermost shell is complete

Inert Elements

Atoms are stable (inert) when the outermost shell is complete

Atoms will gain, lose, or share electrons to complete their outermost orbitals and reach a stable state

Inert Elements

Atoms are stable (inert) when the outermost shell is complete

Atoms will gain, lose, or share electrons to complete their outermost orbitals and reach a stable state

Atoms are considered stable when their outermost orbital has 8 electrons (With exception to the first shell

Inert Elements

Reactive ElementsValence shells are not full and are unstable

Tend to gain, lose, or share electronsAllow for bond formation, which produces stable

valence

Molecules and Compounds

Molecule: Two or more like atoms combined chemically

Compound: Two or more different atoms combined chemically

Molecules and Compounds

https://phet.colorado.edu/en/simulation/build-a-molecule

What are chemical reactions?What do you remember?

What are chemical reactions?

Atoms are united by chemical bonds

OR

Atoms dissociate from other atoms when chemical bonds are broken

Chemical Bonds

Ionic vs. Covalent

https://www.youtube.com/watch?v=fHGSSV466Gk

Ionic Bonds

Form when electrons are completely transferred from one atom to another

IonsCharged particles

Anions - negativeCations - positiveEither donate or accept electrons

Ionic Bonds

+ –

Sodium atom (Na)(11p+; 12n0; 11e–)

Chlorine atom (Cl)(17p+; 18n0; 17e–)

Sodium ion (Na+) Chloride ion (Cl–)

Sodium chloride (NaCl)

ClNaClNa

Covalent Bonds

Atoms become stable through shared electrons

Single covalent bonds share one pair of electrons

Double covalent bonds share two pairs of electrons

Covalent Bonds - Example

Covalent Bonds - Example

Covalent Bonds - Example

Covalent vs. Ionic bonds

https://phet.colorado.edu/en/simulation/sugar-and-salt-solutions

Covalent vs. Ionic bonds

• https://www.youtube.com/watch?v=mHKGLawOTww

• https://www.youtube.com/watch?v=9WXTbkBGPrE

• https://www.youtube.com/watch?v=dD0Xl4acUFg

Polarity

Covalently bonded molecules

Polarity

Some are non-polarElectrically neutral

as a molecule

Some are polarHave a positive and

negative side

Polarity

https://phet.colorado.edu/en/simulation/molecule-polarity

Hydrogen bonds

Weak chemical bonds

Hydrogen is attracted to the negative portion of polar molecule

Provides attraction between molecules

Hydrogen bonds

Hydrogen bonds

How many drops of water can you fit on a penny?

Who can guess correctly??