Unit 1 – Section B Looking at Water and Its Contaminants

Unit 1 – Section B

Looking at Water and Its Contaminants

HW

Read & take notes on sectionsB.1

B.2 Answer questions (1-3) on pg. 28, be prepared to discuss them.

B.3

B.1 Physical Properties of Water

Matter – is anything that occupies spaceAll solids, liquids and gases are classified as matter.

Physical properties are those that can be observed without changing the chemical make-up of a substance.Density which is the mass of a given material within

a given volume is an example of a physical property.

B. 1 Physical Properties of Water(continued)

Other examples of physical properties:– Freezing point \ melting point– Appearance– Texture– Color– Odor– boiling point, – Solubility– polarity, and many others.

B.1 Physical Properties of Water(continued)

Many substances dissolve readily in water, many liquids are water solutions, such water-based solutions are called aqueous solutions.

Examples: cola, saltwater, rain

B. 2 Density

Answer questions (1-3) on pg. 28, be prepared to discuss them.

B. 3 Mixtures and Solutions

A mixture is two or more substances combined that retain their individual properties.Examples: foul water (from our lab)

More specifically the foul water was an example of a heterogeneous mixture because the composition is not the same , or uniform throughout the mixture.

B. 3 Mixtures and Solutions (continued)

Another example of a heterogeneous mixture is called a suspension, this is when solid particles may settle out or be removed as we did by filtration.Example: coffee


When particles of a heterogeneous mixture are even smaller and do not settle out – the solution may appear cloudy. This scattering of light is known as the Tyndall effect. The type of mixture is know as a colloid. Examples: whole & low-fat milk, cream

Butterfat particles not visible to naked eye, but may be seen under high magnification and appear as suspended globules.


Tyndall Effect

Image source : http://silver-lightning.com/tyndall/


When particles of a heterogeneous mixture are even more small and cannot be seen even using magnification and they do not scatter light (the Tyndall effect). This is known as a homogeneous mixture. A mixture uniform throughout.


All solutions are homogeneous mixtures.

Examples: vinegar, rubbing alcohol, food coloring


In a salt solution the salt is the solute (dissolved substance) and the water is the solvent (dissolving agent).

All solutions consist of one or more solutes and a solvent.

Examples: sugar (solute) into tea (solvent)

B.1-B.3 Quiz

HWRead & take notes on sections

B.4B.5

Illustrate and complete questions (1-7) on pgs. 33-34, be prepared to discuss them.

B. 4 Particulate View of Water

Exploring at the level of atoms and molecules is considered the particulate level.

All matter is composed of atoms.

Matter made up of only one kind of atom is known as an element.Examples: Helium (He) , Gold (Au)

Let’s Meet the Elements!

B. 4 Particulate View of Water(continued)

A substance composed of two or more atoms linked chemically in certain fixed proportions is a compound.Examples: water (H2O), salt (NaCl)

Chemists have identified > 24,000,000 compounds


Compounds and elements are represented by their chemical formula.Examples: of familiar formulas ammonia (NH3),

baking soda (NaHCO3)

chalk (CaCO3)

sugar (C12H22O11)


Each element and compound is considered a substance because each has a uniform and definite composition.

The smallest unit of a molecular compound that retains the properties of that substance is a molecule.Examples: oxygen (O2) 2 atoms of oxygen

ammonia (NH3) 1 atom of nitrogen & 3 atoms of hydrogen

B. 5 Pictures in the Mind

Macroscopic world – a world filled with large-scale readily observable things.

A model is any simplification, substitute or stand-in for what you are actually studying or trying to predict.

B. 5 Pictures in the Mind(continued)

Sample: Draw a model of two gaseous compounds in a homogeneous mixture.

A homogeneous mixture is uniform throughout so it needs to be:• Intermingled• Evenly distributed

B. 5 Pictures in the Mind(continued)

Illustrate and complete questions (1-7) on pgs. 33-34, be prepared to discuss them.

B.4-B.5 Quiz

HW

Notes on B.6 and Answer B.7 questions (1-3) on pgs. 36-37, be

prepared to discuss them.

B. 6 Symbols, Formulas and Equations

Each element is assigned a chemical symbol. –Understood by scientist throughout world–First letter capitalized

Examples: carbon (C), calcium (Ca)

The symbols for the 5 most common elements in the Universe1.H2.He3. O 4.C5.Ne

B. 6 Symbols, Formulas and Equations (continued)

All known elements are organized into the periodic table of elements.

http://www.funbrain.com/periodic/index.html


Chemical formulas represent the different chemical substances.

Example: sugar

C12H22O11

Chemical symbol represents each chemical present

A subscript indicates how many atoms are present in one unit.


Chemical equations summarize the details of a particular chemical reaction.

Chemical reactions involve the breaking and forming of chemical bonds, causing atoms to rearrange into new substances.Example: hydrogen and oxygen become water.

2 H2 + O2 2 H2O


The original starting substances in a chemical reaction are called reactants.

2 H2 + O2 2 H2O

The new substance(s) formed are the products.


A handful of elements exist as two bonded elements of the same atom, these are called diatomic molecules.

Example: hydrogen gas (H2) and oxygen gas (O2)

B. 7 Symbols, Formulas and Equations – Developing Skills

1. a. Name the element represented by each of the symbols

I. PII. NiIII. CuIV. CoV. BrVI. KVII. NaVIII. Fe

b. Which elements in questions 1a have symbols that correspond to their English name?

c. Which is more likely to be the same throughout the world – an element’s symbol or its name?

Phosphorous

Nickel

Copper

Cobalt

Bromine

Potassium

Sodium

Iron

B. 7 Symbols, Formulas and Equations – Developing Skills (continued)

2. Name and number the elements

a) H2O2

b) CaCl2

c) NaHCO3

d) H2SO4

Hydrogen Peroxide = 2 hydrogens and 2 oxygens

Calcium Chloride = 1 calcium and 2 chlorines

Sodium hydrogen carbonate = 1 sodium, 1 hydrogen, 1 carbon & 3 oxygens

Sulfuric acid = 2 hydrogens, 1 sulfur & 4 oxygens


3. The burning of methane

CH4 + 2 O2 CO2 + 2 H2O

• Sentence -

b) Compound/element inventory

Methane and oxygen react to form carbon dioxide and water.

Oxygen is an element all the rest are compounds


3. The burning of methane

CH4 + 2 O2 CO2 + 2 H2O

c) Atom Inventory – d) Model

1 carbon, 4 hydrogens + 4 oxygens 1 carbon, 4 hydrogens + 4 oxygens

+ +

B.6-B.7 Review

NH3

ammonia

How many molecules? ______________

How many elements? _______________

How many atoms? __________________

What element has the most atoms in this formula?______________

What is the common name of this formula?______________

B.6-B.7 Review

NaHCO3

baking soda



How many atoms? __________________





How many atoms? __________________



B.6-B.7 Review

CaCO3

chalk

B.6-B.7 Quiz

HW

Notes/read B.8 & B.9 and Create the table as directed on pg. 41, be prepared to discuss your answers.

B. 8 The Electrical Nature of Matter

How do the atoms of molecules stick together?

B. 8 The Electrical Nature of Matter(continued)

Like charges repel

+ +

- -


Unlike charges attract

+ -


Electrically neutral (uncharged) atoms contain equal number of (+) protons and (-) electrons.

Example: electrically neutral sodium has 11 p+ and 11e-


In addition to electrons and protons most atoms contain one or more electrically neutral neutrons.


The positive-negative attraction between protons in one atom and electrons in another atom provides the attachment that hold atoms together.

B.9 Ion and Ionic Compounds

Earlier we learned about molecules, which make up one type of compound. Another type is made up of ions, which are electrically charged atoms

or groups of atoms.

Example: Sodium easily loses one e- leaving it with a positive charge Na+ and chlorine easily gains an e- leaving it with a

negative charge Cl-

B.9 Ion and Ionic Compounds(continued)

Ionic compounds are substances composed of positive and negative ions.

Example: Table salt NaCl


Table salt (NaCl) consists equal numbers Na+ and Cl- arranged in a 3-dimensional network called a crystal.


A negatively charged ion is called an anion.Example: Cl-

A positively charged ion is called a cation.Example: Na+


An ion may be a single atom such as a cation (Na+) or an anion (Cl-).

Ions may also be a group of bonded atoms such as, ammonium cation (NH4

+) or a nitrate anion (NO3

-),

these are called polyatomic ions.


You write formulas for ionic compounds following 2 simples rules:

1. Cation 1st, then anion.2. Correct formula will contain fewest positive and

negative ions in order to make the total electrical charge ZERO.

B. 10 Ionic Compounds – Developing Skills

Create the table as directed on pg. 41, be prepared to discuss your answers.

B. 10 Ionic Compounds – Table

# Cation Anion Formula Name

1 CaSO4

2 Ca2+ PO43-

3 Ammoniumnitrate

4 Al2(SO4)3

5 Magnesiumhydroxide

6 Calcium carbonate

B.8-B.10 Quiz

B. 11 Water Testing - Lab

Documents

Unit 1 – Section B Looking at Water and Its Contaminants