Basic Chemistry

An introduction

Vocabulary

• elements- single substances that can not be broken down into simpler substances

• atom- smallest particle of an element that still has all of the properties of that element

• Ion – an atom with a (+) or (-) charge• symbol- letter or letters representing an element • compound- the chemical combination of two or

more elements • molecule- smallest part of a compound which

still has all of the properties of that compound

Atoms and Subatomic Structure

• Atoms are the basic building blocks of all matter in the universe– Your desk– Your paper– YOU! are made up of atoms

• Atoms are made up of 3 subatomic particles: – Protons - carry a positive charge (+)– Neutrons – carry no charge (no charge) – Electrons – carry a negative charge(-)– Protons and Neutrons are found together at the

center of the atom in the nucleus

Layout of the atom

Nucleus – holds the Protons and Neutrons and is found in the center of the atom.

Electron energy levels (shells)– This is the most likely place you would find an electron.

- 1st electron shell holds 2 electrons

- 2nd electron shell holds 8 electrons

- 3rd electron shell holds 8 electrons

Valance shell (energy level) – the outer most electron shell of an atom.

Mass of subatomic structures

• Protons and neutrons have an almost equal mass of 1

• Electrons are much smaller and lighter and have a mass of approximately 1/1836 of the mass of a proton

Quarks – The makeup of Protons and Neutrons

• Protons and Neutrons are made up particles called quarks.

• These quarks are held together by other particles called gluons

Atoms and Ions

• All atoms are neutral – meaning that however many protons (+) there are there is and equal number of electrons (-)– Ion – is an atom with a charge (when an

electron is lost or gained) – When an atom loses an electron (-) it will

have a +1 charge - When an atom gains and electron (-) it will

have a - 1 charge

Atomic Mass and Atomic Number

• Atomic Number – is the number of protons in an element

• Atomic Mass – is the number of protons plus the number of neutrons in an element (Mass number)

• Number of Neutrons – to find the number of neutrons in an atom subtract the atomic number from the atomic mass.

• Each element has a different atomic number (ex – Hydrogen has 1 proton in its nucleus and therefore has an atomic number of 1)

Finding Neutrons, Protons, and Electrons

Ex 1. Carbon – Atomic number = 4 Atomic mass = 8

Find Protons, Neutrons, and ElectronsP (+) = 4 N = 4E (-) = 4Ex 2. Oxygen – Atomic Number = 8

Atomic Mass = 17P (+) = 8N = 9E (-) = 8

Isotopes

• Isotopes – an atom that differs only in its number of neutrons in the nucleus. – This does NOT change the element – This only changes the atomic mass– EX. Oxygen has an atomic mass of 16, 17,

and 18 • All of these are Oxygen atoms just with a different

number of neutrons in the nucleus

Carbon Isotopes

Goal of all Atoms

• The goal of all atoms is to have a stable outer energy level. This goal leads to the bonding of atoms.

• Bonding can happen two ways. – Sharing of valence electrons – Transfer of valence electrons

Bonding

• 2 Types of Bonding • Covalent bonding – when 1 or more electrons are

SHARED between atoms » Ex. Water (H2O) – Hydrogen and Oxygen each

share 1 electron

• Ionic Bonding – when 1 or more electrons are TRANSFERRED between atoms

» Ex. Salt (NaCl) – Sodium looses an electron making it a +1 ion and Chlorine gains an electron making it a - 1 ion. Opposites attract and an ionic bond is formed

Examples of Bonding

Chemical and Structural Formulas

• Chemical Formula – each element is represented by its chemical symbol and the number of atoms is shown in subscripts. Ex. H2O, CO2, CH4, C6H12O6

• Structural Formula – it show the chemical symbol of each element and how they are bonded to one another.

Structural Formula

Amino Acid Structural Formula

Chemical reactions

• Chemical change or chemical reactions – whenever different substances are formed a chemical change or reaction has occurred– Reactants – substance that were present

before the chemical reaction– Products – the new substances produced by

the chemical reaction

Reactants Products

Law of Conservation of Mass

• Law of Conservation of mass – states that mass can neither be created or destroyed.

- Because atoms have mass they cannot be created or destroyed they can only be rearranged.

EX Law of Conservation of Mass

pH Scale

• A scale which measures the amount of H+ ions solution.– The greater the H+ ions in a solution has the

greater the acidity – The greater the OH – ions in a solutions the

greater the Basicity– When H+ ions = OH - ions the solution is

neutral and water is formed. (H2O)

pH Scale

Indicators

• Benedicts solution (must heat before use)– indicator for glucose, its initial color is blue and the final color (if

sugar is present) is orange/red

• Lugols Iodine – Indicator for starch, its initial color is amber and the final color (if

starch is present) is blue or black

• Buirets Solution – Indicator for protein. Its initial color is blue and the final color (If

protein is present) is purple

• Indicators are used to help us determine is something is an acid or a base – Litmus paper – shows base or acid – pH paper – shows actual pH of acid or base