Chemical Use in Humans and Animals

• The way books utilize real life examples and connections is a way to support the concepts covered in a chapter or module
• Illustrating how a living organism harnesses the power of chemicals is important
• Making connections to relatable everyday events allows approach to more difficult concepts
• All life is made of matter which takes up space and has mass
• Matter consists of elements which are pure substances containing only one kind of atom
• Atoms will be discussed in more detail in module 2
• Matter consists of chemical elements in pure form and in combinations
• A compound consists of two or more elements in a fixed ratio
• A compound has properties, characteristics, and differences from the elements that generated it
• Sodium plus chlorine yields sodium chloride
• Sodium is a solid metal, chlorine is a poisonous gas, but combined the result is ingestible salt

Elements in the Human Body

• Elements have their own distinct properties shift when they combine to form a compound
• Table 2.1 highlights elements in the human body within living systems of a biology-focused perspective
• There are 11 elements within the naturally occurring ones that are present in levels higher than trace amounts
• Trace amounts are anything less than 0.01% of body mass
• Oxygen, carbon, hydrogen, and nitrogen make up 96.3% of body mass
• Oxygen is the most abundant element in the body and is supported by the most common molecule of water
• Organic molecules within the body contain carbon
• Nitrogen is in high abundance for proteins
• Sodium potassium pumps facilitate the movement of ions across the membrane
• Calcium and phosphorus are components of skeletons and shells
• The goal isn't to memorize percentages, instead, look for a theme
• Focus on element application, not memorization
• Elements repeat themselves in module 2 and an element's properties depend on the structure of its atoms

Subatomic Particles

• Form is important to behavior and helps predict behaviors within a living organism
• An element is composed of a unique organization of atoms
• An atom is the smallest unit of matter, takes up space, has mass, and retains the properties of an element
• Atoms are composed of subatomic particles
• Within the nucleus are two of the three subatomic particles
• Protons are shown in pink
• Neutrons are shown in brown
• Protons and neutrons are held in close proximity
• Protons carry a positive charge (+)
• Neutrons have no charge
• The third subatomic particle is the electron
• Electrons have a negative charge
• Electrons are found in regions called orbitals and can be found at varying distances around the nucleus
• Electrons stay near the nucleus because of their attraction to the positive charge of the protons
• Illustration shows the amount of electrons
• An atom typically has one electron for each proton
• 2 electrons and protons yields an electrically neutral atom since the negative and positive charges cancel each other out

Electron Configuration

• The chemical behavior of the atom is based on the number and electron configurations
• Element differ based on the number of protons found within their nucleus
• Helium (He) has two protons
• This is the element's atomic number, and an atom of helium will always have two protons
• Atomic mass is the element's total mass and can be approximated by the mass number
• Element mass number is the sum of protons and neutrons
• Measurement of the amount of a substance shouldn't be confused with weight
• Atomic mass units are measured in daltons
• Isotopes are forms of elements that differ with respect to the number of neutrons that they contain
• Hydrogen has 1 proton
• The superscript value represents the sum of protons and neutrons
• The subscript or lower value is the atomic number
• Isotopes are the same element, not a variation of it and that is due to an amount of neutrons that are present

Isotopes

• Isotopes of an atom have similar chemical properties, but can have different physical properties
• Isotopes can be unstable, which can affect how it behaves over a period of time
• Deuterium is stable, while tritium is very unstable
• Isotopes are atoms of a chemical element with a different number of neutrons
• Radio isotopes are an isotope that lacks stability
• Radio isotopes spontaneously give off energy through radiation
• High levels of radioactivity can be harmful and can damage cells as well as DNA
• Radioisotopes can label or track molecules allowing researchers to track or trace events

Glucose Metabolism

• Positron emission tomography (PET) scan, accomplished by using a radioactively labeled glucose molecule known as Fluorodeoxyglucose (FDG)
• Cancer cells take up glucose at a significantly higher rate than normal tissues
• It is possible to assess cancerous cells within the body from glucose intake
• High amounts of that flower floral glucose indicate a potentially cancerous site within the body
• Radioactive isotopes have a rate of decay that is constant and expressed as the isotope's half-life
• Carbon 14 contains 8 neutrons and is used for carbon dating of fossils/inorganic materials
• P32 has a half-life of about 14 days

Electron Behavior

• The behavior of electrons within an atom determine how it will combine or interact with other atoms
• The emphasis of a biological discussion hinges upon electron behavior associated with the types of chemical reactions within an organism
• Electrons are found in the region of space surrounding the atomic nucleus
• This space is referred to as their orbital, which can have specific shapes and orientations
• Focus will be on the energy level seen in different regions of space
• Energy is the capacity to cause change
• Potential energy is the energy matter has based on its location and structure
• Amount of energy electrons has is related to its distance from the nucleus
• An electron's state of potential energy is called its energy level or electron shell
• Energy increases as you progress further away from the atomic nucleus
• The chemical behavior of an atom is determined by the distribution of electrons within their electron shells
• Periodic table shows elements and their electron distribution
• Valence electrons are the electrons found in the outermost shell, which is farthest away from the atomic nucleus and has the highest energy level

Inert Elements

• Chemical behavior of an atom is primarily determined by valence electrons
• Elements with a complete or full valence shell are chemically inert
• Inert elements have 8 electrons within their last shell such as neon and argon
• For helium the maximum occupancy for it to be an inert element is 2
• Inert means to be non-reactive
• Atoms with incomplete valence shells can share or transfer valence electrons with certain other atoms
• Interactions allow for atoms to stay in close proximity to one another and these attractions are referred to as chemical bonds
• Formation and function of molecules depends on chemical bonding between atoms
• Molecular Hydrogen is a group of atoms held together in a stable association by energy
• Covalent bonds build stable molecules
• 2 hydrogen atoms in proximity to one another will attract to both nuclei and begin to share electrons resulting in a diatonic molecule of hydrogen gas
• New molecule contains 2 protons and 2 electrons maintaining the net-charge

Octet Rule

• Fulfilling the valence shell requirement is referred to as the octet rule
• In oxygen, if we are outside of the first shell we need to reach 8 electrons
• Sharing 2 pairs of electrons to have a double covalent bond is required
• A covalent bond's strength depends on how many electrons shared, so a double bond is stronger
• Comparatively speaking double bonds will need more energy to break as compared to a single bond
• The strongest covalent bond would a triple bond which is seen with nitrogen gas
• Bonds will produce molecules so hydrogen gas and oxygen gas are a result of this by definition
• Molecular goals remain the same with how there is completion of the outer shell as well as stability
• The degree of electron sharing can vary between atoms and this can also impart particular behavior

Ionic bonds

• Atoms strip electrons from their bonding partners, rather than share them
• In transfer, an electron from a sodium atom goes to a chlorine atom
• The chlorine atom now needs 1 electron in order to be satisfied
• The sodium atom is now reducing it back down to the second shell, as opposed to the third
• The removal of electrons forms an ionic bond
• Sodium ions will be a positive charge loss of electron
• Chloride ions will be an anise or be negatively charged
• Sodium has been oxidized and chlorine has been reduced
• Compounds are now formed by this process removal of electrons
• Salts are in this category
• Crystalline structures that we see are the organization of a crystal
• Crystal formations are based on the attraction of ions
• Opposites attract so that the level of interaction takes place
• Very strong covalent bonds exist
• H20 and NH3 both display this property of electronegativity
• Electronegativity increases as you move from left to right across the periodic table and decreases as you work down

Hydrogen bonds

• The upper right corner of the periodic table is the area of highest electronegativity
• The degree of sharing of electrons can be defined as the property of electronegativity
• Region of partial negative (electrons spend more time) as opposed to partial positive due to electrons spending less time
• Electronegativity is related to affinity or desire
• The unequal time will create regions of equal parts protons as well as equal parts electrons which create a region of equal positivity
• Partial negatives are based on distance between electrons
• The atoms can share the attraction of a weak chemical association
• Covalent bonds use a solid line, while hydrogen bonds do not
• Hydrogen is usually bonded to oxygen or nitrogen, but doesn't have to be.
• The electron distribution leads to attractive forces
• Uneven distribution of electron molecules results in imbalance
• Attractions that result from molecular closeness are weak

Gecko Example

• Vander walls exist when attraction is temporary
• Proximity plays role, increases through atoms
• Can be used when a gecko climbs a wall

Molecular Shape and Function

• Molecular shape and function is the underlying theme
• It determines if biological molecules can be recognized
• So shape as well a as size allows something to function
• Reactants that are more complex need different levels etc
• The earlier image of the Ant releasing formic acid to now start to layer our discussion that we've had so far will dictate element consistency

Formic Acid

• Formic acis is composed of carbon and oxygen
• We know how many protons dictate which element they are and that that is consistent
• Lets consider how different the properties for glucose
• With 8 protons, the identity is thus oxygen
• 8 Protons is looking at something that is going to be a neutral
• There's two empty spots in that valence shell, which gives opportunities for sharing to satisfy the molecular rule and help the carbon bind, too

Explore how both animals and humans utilize chemicals for defense and to impact health or living conditions. Questions cover examples of chemical usage in the natural world and their applications by humans to solve problems and improve well-being.