The Chemistry Of LifeThe Chemistry Of Life

Chemistry of LifeChemistry of LifeLife depends on chemistry.Life depends on chemistry.

When we eat food or breathe oxygen, our body When we eat food or breathe oxygen, our body uses these materials to keep us alive. uses these materials to keep us alive.

Just as buildings are made from bricks, steel, Just as buildings are made from bricks, steel, glass, and wood, living things are made from glass, and wood, living things are made from chemical compounds.chemical compounds.

If the first task of an architect is to understand If the first task of an architect is to understand building materials, then the first task of a building materials, then the first task of a biologist is to understand the chemistry of life.biologist is to understand the chemistry of life.

Periodic Table of the ElementsPeriodic Table of the Elements

AtomsAtoms The study of chemistry begins with the basic unit of matter, the The study of chemistry begins with the basic unit of matter, the

atom. The Greek word atomos, which means unable to cut was first atom. The Greek word atomos, which means unable to cut was first used to refer to matter by the Greek philosopher Democritus nearly used to refer to matter by the Greek philosopher Democritus nearly 2500 years ago. Democritus asked a question.........how small can 2500 years ago. Democritus asked a question.........how small can things be broken down to????things be broken down to????

Atoms are incredibly small: 100 million in a row = 1 cm long. Despite Atoms are incredibly small: 100 million in a row = 1 cm long. Despite its extremely small size, atoms are actually made-up of three its extremely small size, atoms are actually made-up of three smaller parts called sub-atomic particles: Protons (+), Neutrons (o), smaller parts called sub-atomic particles: Protons (+), Neutrons (o), & Electrons (-).& Electrons (-).

The electron is a negatively charged particle (-) with 1/1836 the size The electron is a negatively charged particle (-) with 1/1836 the size of a proton. Electrons are in constant motion around the nucleus of of a proton. Electrons are in constant motion around the nucleus of atoms. They are attracted to the opposite charge of the protons in atoms. They are attracted to the opposite charge of the protons in the nucleus, but remain outside due to the energy of their motion.the nucleus, but remain outside due to the energy of their motion.

The AtomThe Atom

Elements and isotopesElements and isotopes

A chemical element is a pure substance that consists A chemical element is a pure substance that consists entirely of one type of atom. Over 100 elements are entirely of one type of atom. Over 100 elements are known, but only about two-dozen are commonly found in known, but only about two-dozen are commonly found in living organisms.living organisms.

Elements are represented by 1 or 2 letters: H - Elements are represented by 1 or 2 letters: H - hydrogen, Na – sodiumhydrogen, Na – sodium

The number of protons in an atom of an element is its The number of protons in an atom of an element is its atomic number. For example, carbon's atomic number is atomic number. For example, carbon's atomic number is 6. This means that each atom of carbon has 6 protons, 6. This means that each atom of carbon has 6 protons, and consequently, 6 electrons.and consequently, 6 electrons.

Elements and isotopes (cont)Elements and isotopes (cont) Isotopes: Atoms of an element can have different numbers of Isotopes: Atoms of an element can have different numbers of

neutrons. For example, some atoms of carbon have 6 neutrons, neutrons. For example, some atoms of carbon have 6 neutrons, some have 7, and a few have 8.some have 7, and a few have 8.

Atoms of the same element that differ in the number of neutrons Atoms of the same element that differ in the number of neutrons they contain are known as isotopes.they contain are known as isotopes.

The sum of the protons and neutrons in the nucleus of an atom is The sum of the protons and neutrons in the nucleus of an atom is called its mass number. BECAUSE THEY HAVE THE SAME called its mass number. BECAUSE THEY HAVE THE SAME NUMBER OF ELECTRONS, ALL ISOTOPES OF AN ELEMENT NUMBER OF ELECTRONS, ALL ISOTOPES OF AN ELEMENT HAVE THE SAME CHEMICAL PROPERTIES.HAVE THE SAME CHEMICAL PROPERTIES.

Radioactivity???Radioactivity???

IsotopesIsotopes

Chemical compoundChemical compound In nature, most elements are found combined with other elements in In nature, most elements are found combined with other elements in

compounds. compounds.

Scientist show the composition of compounds by a kind of Scientist show the composition of compounds by a kind of shorthand known as a chemical formula.shorthand known as a chemical formula.

Water which has 2 hydrogen atoms for every 1 oxygen atom has a Water which has 2 hydrogen atoms for every 1 oxygen atom has a chemical formula of H2O. chemical formula of H2O.

The formula for table salt is NaCl, meaning that salt has a 1:1 ratio The formula for table salt is NaCl, meaning that salt has a 1:1 ratio of sodium (Na) and Chlorine (Cl). of sodium (Na) and Chlorine (Cl).

The physical and chemical properties of compounds are usually The physical and chemical properties of compounds are usually very different from the elements that formed them.very different from the elements that formed them.

Chemical BondsChemical Bonds The atoms in compounds are held together by chemical bonds. The atoms in compounds are held together by chemical bonds.

Much of chemistry is devoted to understanding how and when Much of chemistry is devoted to understanding how and when chemical bonds form. chemical bonds form.

Bond formation involves the electrons that surround each atomic Bond formation involves the electrons that surround each atomic nucleus.nucleus.

The electrons that are available to form bonds are called valence The electrons that are available to form bonds are called valence electrons.electrons.

The main types of chemical bonds are ionic bonds and covalent The main types of chemical bonds are ionic bonds and covalent bonds.bonds.

Ionic bonds are formed when 1 or more electrons are transferred Ionic bonds are formed when 1 or more electrons are transferred from one atom to another.from one atom to another.

Ionic Bonds Ionic Bonds (transferred of electrons)(transferred of electrons)

Chemical Bonds Chemical Bonds (cont)(cont) Sometimes electrons are shared by atoms instead of Sometimes electrons are shared by atoms instead of

being transferred. being transferred.

What does it mean to share electrons? It means that the What does it mean to share electrons? It means that the moving electrons actually travel in the orbits of both moving electrons actually travel in the orbits of both atoms. (single, double, triple bonds???)atoms. (single, double, triple bonds???)

The structure that results from the joining of atoms by The structure that results from the joining of atoms by covalent bonds in called a molecule. covalent bonds in called a molecule.

The molecule is the smallest unit of most compounds. The molecule is the smallest unit of most compounds.

Van der Waals Forces & Gecko's grip???Van der Waals Forces & Gecko's grip???

Van der Waals ForcesVan der Waals Forces

Properties of WaterProperties of Water Water is one of the few compounds that is liquid at the Water is one of the few compounds that is liquid at the

temperatures found over much of the Earth's surface. temperatures found over much of the Earth's surface.

Unlike most substances, water expands as it freezes. Unlike most substances, water expands as it freezes. Thus, ice is less dense than liquid water, which explains Thus, ice is less dense than liquid water, which explains why ice floats on the surface of lakes and rivers. why ice floats on the surface of lakes and rivers.

If ice sank to the bottom, the situation would be If ice sank to the bottom, the situation would be disastrous for fish and plant life in regions with cold disastrous for fish and plant life in regions with cold winters. winters.

Like all molecules, a water molecule (H2O) is neutral. Like all molecules, a water molecule (H2O) is neutral. The positive charges on its 10 protons balance out the The positive charges on its 10 protons balance out the negative charges on its 10 electrons. However, there is negative charges on its 10 electrons. However, there is more to the story...more to the story...

Water is cohesive (sticky)Water is cohesive (sticky)

POLARITYPOLARITY

With 8 protons in its nucleus, an oxygen atom With 8 protons in its nucleus, an oxygen atom has a much greater attraction for electrons than has a much greater attraction for electrons than does the hydrogen atom with a single proton in does the hydrogen atom with a single proton in its nucleus. its nucleus.

Hydrogen Bonds???Hydrogen Bonds???

1. Water strider?1. Water strider?

2. Double Helix?2. Double Helix?

Hydrogen BondingHydrogen Bonding

Water StriderWater Strider

The EndThe End