Unit 3 – Lecture 1

Levels of OrganizationThe basic unit of living things is a ,

because all organisms are made of them.

Cells, however, have smaller components…and cells make up larger structures that compose [anything with all of the characteristics of life].

cell

organisms

Levels of Organization – cont’dAtomMoleculeBiomolecule

[aka macro-molecule]

Organelle

CellTissueOrganOrgan systemOrganism

Atomsatom - smallest part of an element that still

has all of the element’s characteristicsmade of subatomic particles

“sub-” – under, below, less thanprotons [p+]neutrons [n0]electrons [e-]

Atoms – cont’dTypes of Subatomic Particles[p+] – positively charged subatomic particle

found in the nucleus of an atom[n0] – non-charged subatomic particle

[neutral]found in the nucleus of an atom

[e-] – negatively charged subatomic particlefound outside of the nucleus in energy

levels [aka e- clouds, e- shells, etc]

Atoms – cont’d

Electron Models – cont’d

• Draw • Nucleus• Protons• Neutrons

Bohr Models

Atoms – cont’dElectron Models – Bohr Models

• Draw• Electrons

Electron Levels• *2*• 8…8…

Electron Models [not in notes][not in notes]Lewis Dot Structures

• Draw • Atomic Symbol

• Find # of e-s• = 8 O

Electron Models [not in notes][not in notes]Lewis Dot Structures

• Find # of e-s in valence shell• do this by

subtracting 2 for first shell, then 8, then 8…etc.

• keep going until you have 8 or less e-s

• don’t have to do anything with Protons or Neutrons

O

Electron Models [not in notes][not in notes]

• So…• 8 – 2 = 6• we have 8 or

less.• Once you have 8

or less e-s…• draw the remaining

e-s around the chemical symbol.

• Ta-Da.

OLewis Dot Structures

Atoms – cont’dSometimes, however, elements can also

contain different numbers of their subatomic particles…

isotope – an atom of the same element that has a different number of neutrons than normal“iso-” = equal / the sameex: Carbon-14 [number denotes mass,

NOT charge]

Atoms – cont’dSometimes, however, elements can also

contain different numbers of their subatomic particles…

ion – a charged particlehas more or less electrons than the neutral

elementmore = negative, less = positiveex: Fe2+ [number denotes charge w/ + or -

]

PracticeAtomic # =

17# of Protons?# of Electrons?

Atomic Mass = 35# of Neutrons?

18

PracticeBohr Model

draw nucleusprotons = 17neutrons = 18

draw electron shells# of electrons = 17first shell = 2second shell = 8third shell = 7

PracticeLewis Structure?

chemical symbol# of electrons

= 17subtract 2

= 15subtract 8

= 7this is less than 8we have 7 electrons around the symbol

don’t have to worry about protons or neutrons.

Acids & BasespH = parts of hydrogen

concentration of hydrogen ionsAcid – compound which releases hydrogen

ions [H+] in waterpH = 0 – < 7stronger acids release more [H+] ionsEx: HCl [hydrochloric acid]Other facts?

Acids & Bases – cont’dBase – compound which releases hydroxide

[OH-] in waterpH = >7 – 14stronger bases release more [OH-] ions Ex: NaOH [sodium hydroxide]Other facts?

***NOT IN NOTES BUT NOT NEEDED: ***NOT IN NOTES BUT NOT NEEDED: pOH – parts hydroxide - not often used, pOH – parts hydroxide - not often used, but can be calculated***but can be calculated***

Acids & Bases – cont’dNeutral - compound that breaks apart in

water and releases the same number of [H+] and [OH-]pH = exactly 7some experiments define what a “neutral

range” could be [roughly pH of 7]

Acids & Bases – cont’dEqual Strength Acid + Equal Strength Base =

Neutral hydrogen and hydroxide ions are equal in

strength.[H+] + [OH-] HOH (hydrogen hydroxide)

(water…H2O)HCl + NaOH

NaCl (sodium chloride/table salt) +

H2O

Acids & Bases – cont’d***ALSO NOT IN NOTES – COPY DOWN***ALSO NOT IN NOTES – COPY DOWNIndicator – used to identify whether a

substance is an acid or a baseshows this by a color changeExamples:Bromophenol Blue

Red Cabbage water

Acids & Bases – cont’d Examples – cont’d

litmus paper / pH test stripsred in acid, blue in base