Protons, Electrons, and Protons, Electrons, and NeutronsNeutrons
Protons, Electrons, and Protons, Electrons, and NeutronsNeutrons
Charges:Charges: ElectronsElectrons - Negatively charged - Negatively charged ProtonsProtons - Positively charged - Positively charged NeutronsNeutrons – Neutral (no charge) – Neutral (no charge)
Be9.01
Beryllium
4
Element NameElement Name
Atomic NumberAtomic Number
Element SymbolElement Symbol
Atomic MassAtomic Mass
(# of protons and electrons)
(# protons + # neutrons) protons)
Mass Number - Atomic Number = # of neutrons
++
++
9 - 4 = 5
(# protons)
Cl35.45
Chlorine
17171719
P =E =N =
What are the numbers of protons, electrons and neutrons?
Protons =
Electrons =
Neutrons =
17
17
18
Where are protons, electrons, Where are protons, electrons, and neutrons located?and neutrons located?
Protons –inside the atomic nucleus
Neutrons –inside the atomic nucleus
Electrons –orbit the atomic nucleus
Electrons Protons and Neutrons
IsotopesIsotopes Different atoms of the same element Different atoms of the same element
# Protons stays the same # Protons stays the same # Neutrons are different# Neutrons are different
Ex. Carbon 12 – 6P, 6N, 6EEx. Carbon 12 – 6P, 6N, 6E Carbon 13 – 6P, 7N, 6ECarbon 13 – 6P, 7N, 6E
Carbon 14 – 6P, 8N, 6ECarbon 14 – 6P, 8N, 6E
The have the same # electronsThe have the same # electrons
The chemical properties don’t The chemical properties don’t change change
Chemical BondsChemical Bonds1.1. Ionic Bonds Ionic Bonds –formed b/w –formed b/w
oppositely charged ionsoppositely charged ions An atom that loses An atom that loses
electrons has a + electrons has a + chargecharge
An atom that gains An atom that gains electrons has a – electrons has a – chargecharge
IonsIons- Positively and - Positively and negatively charged negatively charged atomsatoms
2. 2. Covalent BondsCovalent Bonds- electrons - electrons are shared b/w atomsare shared b/w atoms When atoms share 2 When atoms share 2
electrons => single electrons => single covalent bondcovalent bond
When atoms share 4 When atoms share 4 electrons => double electrons => double covalent bondcovalent bond
Water and pH Water and pH
WaterWater
Covers 3/4 of Earth's surface Covers 3/4 of Earth's surface The single most abundant compound in The single most abundant compound in
most living thingsmost living things One of the few compounds that is a liquid One of the few compounds that is a liquid
at the temperatures found on the Earth's at the temperatures found on the Earth's surface surface
Density of WaterDensity of Water Unlike most substances, Unlike most substances,
water expands as it freezeswater expands as it freezes Ice is less dense than liquid Ice is less dense than liquid
water and therefore floatswater and therefore floats If ice sank it would be If ice sank it would be
disastrous for: disastrous for: 1.1. fish and plant life in regions w/ fish and plant life in regions w/
cold winterscold winters
2.2. sport of ice skating sport of ice skating
Polarity: The Water Polarity: The Water MoleculeMolecule
Water is a Water is a polarpolar molecule molecule Due to the unequal sharing Due to the unequal sharing
of electronsof electrons• The oxygen end has a slight (-) The oxygen end has a slight (-)
chargecharge• The hydrogen end has a slight The hydrogen end has a slight
(+) charge (+) charge • http://programs.northlandcollege.
edu/biology/Biology1111/animations/hydrogenbonds.html
+-
Hydrogen BondsHydrogen Bonds Polar molecules, such as HPolar molecules, such as H220, attract each other 0, attract each other
because of their partial (+) and partial (-) chargesbecause of their partial (+) and partial (-) charges This is a This is a hydrogen bondhydrogen bond Not as strong as covalent or ionic bondsNot as strong as covalent or ionic bonds
Because it is only b/w partial chargesBecause it is only b/w partial charges
Properties of WaterProperties of Water
The ability of water to form multiple The ability of water to form multiple hydrogen bonds is responsible for many of hydrogen bonds is responsible for many of water's propertieswater's properties One water molecule may be involved in 4 One water molecule may be involved in 4
hydrogen bonds at the same timehydrogen bonds at the same time
Properties of WaterProperties of Water
1.1. CohesionCohesion- an attraction b/w molecules - an attraction b/w molecules of the same substanceof the same substance
Why drops of water form beads on a smooth Why drops of water form beads on a smooth surfacesurface
Also explains why some insects and spiders Also explains why some insects and spiders can walk on a pond's surfacecan walk on a pond's surface
• AKA “Surface Tension”AKA “Surface Tension”
Properties of Water (Cont’d)Properties of Water (Cont’d)
2. 2. AdhesionAdhesion- an attraction b/w molecules of - an attraction b/w molecules of different substances different substances The meniscus in a graduated cylinder The meniscus in a graduated cylinder
• Forms because adhesion b/w water molecules and Forms because adhesion b/w water molecules and glass molecules is stronger than the cohesion glass molecules is stronger than the cohesion between water moleculesbetween water molecules
Capillary ActionCapillary Action• Adhesion also causes water to rise in a narrow Adhesion also causes water to rise in a narrow
tube against the force of gravitytube against the force of gravity• One of the forces that draw water out of the roots One of the forces that draw water out of the roots
of a plant and up into its stems and leavesof a plant and up into its stems and leaves
MixturesMixtures
Mixture-Mixture- a material composed of 2+ a material composed of 2+ elements or compounds that are physically elements or compounds that are physically mixed together but not chemically mixed together but not chemically combinedcombined Examples - Salt & pepper or a SaladExamples - Salt & pepper or a Salad Cookies and Cream Ice CreamCookies and Cream Ice Cream
SolutionsSolutions SolutionSolution - Mixture of 2+ substances where - Mixture of 2+ substances where
the molecules of the substances are the molecules of the substances are evenly distributed evenly distributed SoluteSolute - substance that is dissolved (ex. salt) - substance that is dissolved (ex. salt) SolventSolvent - substance in which the solute - substance in which the solute
dissolves (ex. water)dissolves (ex. water)
**Water is the universal solvent
because of its polarity
pH ScalepH Scale
A water molecule can react to form ionsA water molecule can react to form ions
The The pH scalepH scale is used to indicate the is used to indicate the concentration of H+ ions in solution concentration of H+ ions in solution
pH stands for “power of Hydrogen” pH stands for “power of Hydrogen”
OHH
OH-
If If moremore H H++ than OH-, the chemical is an ACID than OH-, the chemical is an ACID
If If lessless H H++ than OH-, the chemical is a BASE than OH-, the chemical is a BASE
If equal amounts of H+ and OH-, the chemical is NEUTRAL
OHH
OH-
OHH
OH-
HH++
HH++
HH++
00
11
22
33
44
55
77
88
99
1010
1111
1212
1313
1414
More
Aci
dic
H+
More
Basi
c O
H-
Neutral66
• Litmus paper is used as an indicator for acids and bases
Acids turn blue litmus to red Bases turn red litmus to blue
An acid with a pH of 1 is stronger than one with a
pH of 6
A base with a pH of 14 is stronger than a base with
a pH of 8