Transcript Atoms, Acids & Bases

Unit 3 – Lecture 1
Levels of Organization
The basic unit of living things is a cell , because all
organisms are made of them.
Cells, however, have smaller components…and cells
make up larger structures that compose organisms
[anything with all of the characteristics of life].
Levels of Organization – cont’d
 Atom
 Cell
 Molecule
 Tissue
 Biomolecule
 Organ
 [aka macro-
molecule]
 Organelle
 Organ system
 Organism
Discuss
 What are the three types
of subatomic particles?
[the three particles that make up an atom]
 What are their charges?
Atoms
 atom - smallest part of an element that still has all of
the element’s characteristics
 made of subatomic particles
 “sub-” – under, below, less than
 protons [p+]
 neutrons [n0]
 electrons [e-]
Atoms – cont’d
Types 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 particle
 found outside of the nucleus in energy levels
[aka e- clouds, e- shells, etc]
Atoms – cont’d
 Elements are made of atoms.
 element – a pure chemical substance consisting of a
singular type of atom.
 found on the periodic table in their neutral state
• atomic number – p+ (also # e- bc neutral)
• chemical symbol – name of element
• atomic mass – mass of p+ plus mass of n0
Discuss
 The atomic # of an element
represents what about the atom?
 The atomic mass of an element
represents what about an atom?
 If looking at a periodic table, which is the larger # in
each element box – the atomic #, or the atomic mass?
 What is the atomic mass of
the elements to the right?
Atoms – cont’d
Sometimes, 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 same
 ex: Carbon-14 [number denotes mass, NOT charge]
 [typical carbon has a mass of 12]
Atoms – cont’d
Sometimes, however, elements can also contain different
numbers of their subatomic particles…
 ion – a charged particle
 has more or less electrons than the neutral element
 more = negative, less = positive
 ex: Fe2+ [number denotes charge w/ + or - ]
Practice
 Atomic # =
 17
 # of Protons?
 # of Electrons?
 Atomic Mass =
 35
 # of Neutrons?

18
Discuss
 Define the terms: Ion, Isotope
 How are these two
terms similar? [compare]
 both are describing a difference
in a # of a subatomic particle.
 How are they
different? [contrast]
 ion = difference in electrons
 isotope = difference in neutrons
Acids & Bases
 pH = parts of hydrogen
 concentration of hydrogen ions
 Acid – compound which releases hydrogen ions [H+]
in water
 pH = 0 – < 7
 stronger acids release more [H+] ions
 Ex: HCl [hydrochloric acid]
 Other facts?
Acids & Bases – cont’d
 Base – compound which releases hydroxide [OH-]
in water
 pH = >7 – 14
 stronger bases release more [OH-] ions
 Ex: NaOH [sodium hydroxide]
 Other facts?
***NOT IN NOTES BUT NOT NEEDED:
pOH – parts hydroxide - not often used, but can
be calculated – we’ll never use this***
Acids & Bases – cont’d
 Neutral - compound that breaks apart in water and
releases the same number of [H+] and [OH-]
 pH = exactly 7
 some experiments define what a “neutral range”
could be [roughly pH of 7]
Acids & Bases – cont’d
 Equal 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
 Indicator – used to identify whether a substance is an
acid or a base
 shows this by a color change
 Examples:
 Red Cabbage water
Acids & Bases – cont’d
 Examples – cont’d

pH test strips
 red in acid, blue in base
Discuss
 On the scale of 0-14,
which numbers represent acids?
which numbers represent bases?
 What kind of things help you figure
out if something is an acid or a base?
 What color trends do you see in cabbage water and in
pH strips as you move from acids to bases?
Homework
 Take the remainder of the period and compare answers
to the Acid/Base Webquest, then review your vocab.
 REVIEW YOUR VOCABULARY for homework
 there’s tons of it, so I’m not giving additional work
 this is the hardest unit because there’s so much
vocab – so seriously, take time to learn a few words
tonight!!!