1. Chapter 7: Atoms and Molecules

2. Chemistry
Chemistry is the study of matter and how matter interacts with each other
Matter is made up of small particles called atoms
An atom is the smallest part of matter/an element that can be recognized as that element

3. Atoms Atoms are made of three particles
Nucleus- condensed center of an atom
1. Protons- positively charged particles inside the nucleus of an atom
2. Neutrons- neutral/no charge particles inside the nucleus of an atom
Shells- space surrounding the nucleus of an atom
3. Electron- negatively charged particles travelling around the nucleus of an atom

4. Atomic Number
The atomic number is the number that represents the element- it is the number of protons in a given atom/element
Niels Bohr- developed the Bohr model of an atom that simplifies the structure of an atom

5. Atomic Theory Describes how scientists think about atoms
It states that all matter is made of atoms and that each element has its own characteristics based on the number of particles in it, also reactions occur when these atoms of given elements are rearranged

6. Elements Classifying Elements
Chemical symbols- are abbreviations for the names of the elements
The first letter of a chemical symbol is always a capital letter
The second (and third) letter (s) are always lower case
A capital letter always indicates a new element
CO= Carbon and Oxygen – Carbon monoxide, a gas
Co= Cobalt, a metal

7. Periodic Table of Elements
Dimitri Mendeleev is the chemist responsible for creating the Periodic Table of Elements (POE)
Elements were arranged by atomic weights and space was left for the possible discovery of new elements
The current POE arranges the elements by atomic number (number of protons) and space is still left for possible new elements

8. Periodic Table of Elements
Elements are arranged on the POE in both horizontal rows and vertical columns
Periods- horizontal rows- have some similarities
Groups- vertical columns
Each element in a group has the same number of electrons in the outermost shell
The elements are also classified on the POE by categories called families- based on similar properties shared by all elements in that family

9. Periodic Table of Elements
Families
Alkali Metals
Alkaline Earth Metals
Transition Metals
Inner Transition Metals
Semi-metals or Metalloids
Nonmetals

10. Compounds
When atoms join together with other atoms to form units they are called molecules
The process of combining different types of atoms is called a chemical change or chemical reaction
Compounds- are the products of chemical changes
A combination of 2 or more different atoms types of elements

11. Common Compounds
H2O- water
NaCl- sodium chloride- table salt

12. Chemical Formulas
Chemical formulas are symbols and numbers used to abbreviate the name and number of elements/atoms in a compound
It tells you how the atoms of elements combine and what the compound is
C6H12O6 Table sugar
There are 6 carbon atoms, 12 hydrogen atoms, and 6 oxygen atoms for every sugar molecule

13. Chemical Reactions
Chemical reactions occur between the electrons of atoms
There are several different types of reactions
Synthesis- elements combine
Decomposition- compounds break down
Single replacement- one element replaces another
Double replacement- two elements switch places

14. Chemical Reactions Synthesis- elements combine
Decomposition- compounds break down
Single replacement- one element replaces another
Double replacement- two elements switch places

15. Quick Check p 169 What is a chemical reaction?
Which two substances join to make carbonic acid?
Is carbonic acid a different substance than carbon dioxide and water?
What is this type of chemical reaction called?

16. Quick Check p 169 What is a chemical reaction?
The process through which different types of atoms join together
Which two substances join to make carbonic acid?
Carbon dioxide and water
Is carbonic acid a different substance than carbon dioxide and water?
Yes
What is this type of chemical reaction called?
Synthesis reaction

17. Atomic Bonding
Atoms will bond with each other depending on the number of electrons in their outermost shell.
Each shell can only hold a certain number of electrons and once that is filled the shell is closed and “stable”

18. Covalent Bonds This occurs when atoms share their electrons in pairs
This sharing allows each atom to have the number of electrons they each need to be stable
This occurs most often in gases and liquids; although it can occur, rarely, in metals
O2 and H2O are both examples of covalent bonding

19. Ionic Bonding
Occurs when an electron is transferred from one element to another
When an atom has lost or gained an electron it is called an ion
This is when the number of electrons does not equal the number of protons in the atom’s nucleus
If they lose electrons and there are more protons than electrons it is positive ion (cation)
If they gain electrons and there are more electrons than protons it is a negative ion (anion)

20. Ionic Bonding
When a negative and positive ion are near each other they are attracted to each other and join together
Opposites attract!
This forms and ionic bond

21. Acids and Bases: Acids
Acids form hydrogen ions (H+) when they are dissolved in water
Their strength depends on how many hydrogen ions form
They can be corrosive- able to dissolve metal (i.e. hydrochloric acid)
Examples are lemon juice, vinegar and of course stomach acid
They have a pH of 0-6.9

22. Acids and Bases: Bases
Bases form hydroxide ions (OH-) when dissolved in water
The strength of a base depends on how many hydroxide ions form
They have a pH of
Some are weak and some are strong
Some examples include baking soda and antacids
If a base dissolves in water it is called alkali

23. Acids and Bases: pH Scale
The pH scale means “power” or “potential” of “hydrogen” (puissance de l'hydrogène)
It is a measurement of acidity or alkalinity (bases)
0-6.9 is an acid
7.0 is neutral- neither an acid nor a base
is a base

24. Acids and Bases: Indicators
Acids and bases are usually found in water solutions
An indicator is a substance that will change color when exposed to an acid or a base
Litmus paper is an indictor
Blue litmus changes to red in an acid and has no change in a base
Red litmus changes to blue in a base and has no change in an acid

25. Acids and Bases: Neutralizing Acids and Bases
When an acid and a base come in contact with each other they will neutralize or cancel each other out
An acid will neutralize a base when it is of equal strength and a base will neutralize an acid the same way
When acids and bases come in contact with each other they form salts
A salt is an ionic compound that contains positive ions from a base and negative ions from an acid
Most are made of a metal and a non-metal