basic chemistry an introduction. vocabulary elements- single substances that can not be broken down...
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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