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. - 1 st electron shell holds 2 electrons - 2 nd electron shell holds 8 electrons - 3 rd 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 Electrons P (+) = 4 N = 4 E (-) = 4 Ex 2. Oxygen – Atomic Number = 8 Atomic Mass = 17 P (+) = 8 N = 9 E (-) = 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. H 2 O, CO 2, CH 4, C 6 H 12 O 6 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. (H 2 O)

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