What is Chemistry? -the study of the composition and reactions of matter. What is matter? What are...

What is Chemistry?-the study of the composition and

reactions of matter.

What is matter?

What are the states of matter?

What is matter composed of?

Elements

92 naturally occurring elementsLET’S NAME THEM!

Name the most common elements?

- a pure substance that can not bebroken down or converted to other substances by ordinary chemical means.

NO!

Carbon Hydrogen Oxygen Nitrogen Phosphorus

Sulfur18.5 % 9.5 % 65 % 3.3 %

96.3 % of the human body

What are elements composed of?

Atoms

What are atoms composed of?

- the basic unit of matter

Subatomic particlesProtons- (+) positively charged particles

Neutrons- (0) uncharged particles

Electrons- (-) negatively charged particles

Atoms are neutral

Atomic number of an atom - the number of protons within an atom

Protons and Neutrons have mass

Why? (+) = (-)

Atomic mass of an atom- the protons + neutrons

C126

Atom of Carbon

Isotopes - atoms of the same element that have the same atomic #, but different atomic mass.

C126

Carbon 12 Carbon 14 C146

Radioactive Isotopes- isotopes that have unstable nuclei that decay and emit radiation.

Nuclei with too many neutrons break apart spontaneously (decay), which can be detected

Uses of radioactive isotopes- Labels and Therapy

PET scan

How are subatomic particles arranged?

Ex. Carbon Ex. Chlorine

Which electrons contain the most energy?

Why is electron configuration important?

- Formation of molecules and compounds

Molecule – a stable assembly of 2 or more atoms.

Compound- 2 or more atoms of different elements bonded together in fixed proportions.

Ex. O2

Ex. H2O

How are molecules and compounds formed?

Chemical reactions

Ex. 2H + O H2O

How do they stay together?Chemical Bonds- An attractive force that arise between 2 atoms when their electrons interact.

3 types of Bonds:Ionic, Covalent, and Hydrogen

Ionic Bonds - form when electrons are transferredfrom one atom to another.

Ex. Na + Cl = Na+Cl-

Cl at# = 17Na at# = 11

Ionic Bonds - form when electrons are transferredfrom one atom to another.

Ex. Na + Cl = Na+Cl-

Cl #e- = 18Na #e - = 10

Covalent Bonds - form from the sharing of e-

2 types of covalent bonds:

1. Non-polar covalent bonds - results from the equal sharing of e-

2. Polar covalent bonds - results from the unequal sharing of e-

Ex. H - H

1. Non-polar covalent bonds

Ex. O = O

1. Non-polar covalent bonds

Ex. H2O

2. Polar covalent bonds

Hydrogen bonds- weak electrical attractions between “H” and a negatively charged atom of another molecule.

Water molecules DNA