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Life Sciences
The Chemical Level of Organization
| Question | Answer |
|---|---|
| What is the definition of Chemistry? | The science that deals with the composition and properties of matter. |
| Pharmacology | Drugs used to treat diseases are chemicals and chemistry is used for the development and for understanding their actions in the body. |
| Matter | – is anything that takes up space, materials from which the entire universe is made. |
| Elements | Are the unique substances that make up all matter, food we eat, the atmosphere, water are made up of 92 naturally occurring elements. These include, (gases) hydrogen, oxygen and nitrogen, (solids) iron, aluminum, gold, zinc. |
| Different forms of the element Carbon | Graphite, coal, charcoal and diamond |
| Units of matter of all chemical elements are called | Atoms |
| An element is | a quantity of matter composed of atoms of the same type. |
| Atoms contain: | • Nucleus: protons (p+) & neutrons (no) • Electrons (e-) surround the nucleus as a cloud |
| What forms the nucleus of an atom? | Protons and neutrons |
| Describe protons | large, positively-charged particles |
| atomic number refers to | The number of protons in the nucleus |
| atomic number determines | The element |
| Neutrons are | the second large particle that make up the nucleus of atoms. |
| Unlike protons, neutrons... | Have no charge. |
| What do neutrons add? | Mass |
| How are electrons described to look in relation to the nucleus? | Planet orbiting the sun. |
| What % of an atoms mass is the nucleus | 99.9% (proton nucleus) |
| Most space of an atom is taken up by the | electron cloud |
| Atoms are neutral- why is this? | They have the same number of protons and electrons therefore the positive charge cancels the negative. |
| Ions are | atoms that have given up or gained an electron in their outer electron shell (also called the valence shell) |
| Molecules are formed when | atoms share electrons |
| How are molocules written as | Written as a molecular formula showing the number of atoms of each element (H₂O) |
| The oxygen gas in the atmosphere we breath is really not oxygen the atom, it is what? | A pair of oxygen atoms linked together into an oxygen molecule (O₂). |
| The atoms of a molecule are held together by... | forces of attraction called chemical bonds. |
| What are chemical bonds? | Forces of attraction that hold together a molecule. |
| The likelihood that an atom will form a chemical bond with another atom depends on | the number of electrons in its outermost or valence shell |
| Ionic bonds form when | an atom loses or gains a valence electron. Ions are formed. |
| Positively and negatively charged ions are | attracted to one another |
| Cations are positively charged ions that have | given up one or more electrons (they are electron donors.) |
| Anions are | negatively charged ions that have picked up one or more electrons that another atom has lost (they are electron acceptors). |
| Covalent bonds are | formed by the atoms of molecules sharing one, two, or three pairs of their valence electrons. |
| Covalent bonds are the ............. chemical bonds. | Strongest |
| Single, double, or triple covalent bonds are formed by | sharing one, two, or three pairs of electrons, respectively |
| Covalent bonds may be 'X' or 'Y' | nonpolar or polar. |
| In a nonpolar covalent bond, | atoms share the electrons equally |
| What are the most popular covalent bonds? | nonpolar covalent bonds are the most common types of covalent bonds |
| Polar covalent bonds are formed by | the unequal sharing of electrons between atoms |
| Polar covalent bonds are extremely important because | The all-important water molecule makes use of this bond. |
| In water, oxygen attracts the hydrogen electrons more strongly, making oxygen | slightly electronegative as indicated by the negative Greek delta sign. |
| Hydrogen bonds are strong or weak interactions? | weak interactions (being only 5% as strong as covalent bonds) between hydrogen and adjacent electronegative atoms like oxygen |
| Hydrogen bonds result from | attraction of oppositely charged parts of molecules, they should not be confused with covalent bonding to hydrogen which involves actual sharing of electrons. |
| Hydrogen bonds are useful in establishing | links between molecules or between distant parts of a very large molecule. |
| Large 3-D molecules (like proteins) are often held together by | a great many hydrogen bonds. |
| In water, hydrogen bonding provides | considerable cohesion which creates a very high surface tension |
| Chemical reactions occur when electrons in the valence shell are | shared or transferred. New bonds form and/or old bonds are broken |
| Metabolism is the | “sum of all the chemical reactions in the body”. |
| Types of chemical reactions can be broadly classified as: | • Synthesis reactions – Anabolism • A + B ➙ AB • Decomposition reactions – Catabolism • AB ➙ A + B • Exchange reactions • AB + CD ➙ AD + CB • Reversible reactions • AC ↔ A + C |
| • Synthesis reactions – Anabolism • A + B ➙ AB | Making it |
| • Decomposition reactions – Catabolism • AB ➙ A + B | Breaking it down |
| • Exchange reactions • AB + CD ➙ AD + CB | Exchange Reactions |
| • Reversible reactions • AC ↔ A + C | Unmaking it |
| Inorganic compounds are structurally | simple molecules that usually lack carbon - like the salt potassium chloride (KCl) |
| Organic compounds always contain | carbon and are usually large, complex molecules. |
| Organic compounds (2 facts) | Usually contain hydrogen Always have covalent bonds |
| Water as a solvent: | In a solution (one substance dissolved in another), the solvent dissolves the solute e.g., salt water |
| Substances which contain polar covalent bonds and dissolve in water are | hydrophilic (‘water loving’) gases & nutrients |
| substances which contain non-polar covalent bonds are | hydrophobic (‘water fearing’) fats. |
| The polarity of water and its bent shape allow it to | interact with several neighboring ions or molecules. |
| Water’s role as a solvent makes it essential for | health and survival |
| Water has a high heat capacity, meaning it can | absorb or release a relatively large amount of heat with only a modest change in its own temperature |
| waters high heat capacity is due to | This property is due to the large number of hydrogen ions in water. |
| Water - Heat of vaporization (amount of heat needed to change from a liquid to a gas) | is also high |
| Evaporation of water from the skin removes | large amounts of heat |
| A mixture is a combination of | elements or compounds that are physically blended together but are not bound by chemical bonds |
| In a solution, a substance called the solvent | dissolves another substance called the solute. Usually there is more solvent than solute in a solution |
| In our bodies, the most common solvent is | water: |
| What % of water are humans? | We are 65-80% water (depending on age - babies are very “wet”. |
| In a suspension, the suspended material may | mix with the liquid or suspending medium for some time, but it will eventually settle out (blood is a suspension.) |
| A colloid differs from a solution mainly because the | molecules do not dissolve but remain evenly distributed in the suspending material (cytosol –cell fluid and blood plasma) |
| Many mixtures are complex, with properties of | solutions, suspensions, and colloid |
| Blood Plasma has dissolved compounds | Solution |
| Red blood cells other formed elements | Suspension |
| Proteins in the Plasma | Colloid |
Created by:
paramedicscienceUK
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