Chapter 2 Atoms Flashcards
What is an atom?
The basic unit of matter
What is an isotope?
Atoms of the same element that have a different number of neutrons
Define an ion and provide an example.
An electrically charge atom.
H+ is positively charged because it has lost an electron
Define orbital.
A region in space likely to host an electron
What is an atomic shell?
An energy level within an orbital.
Electron will choose to occupy the shell closest to the nucleus first
What is the periodic table?
Elements are arranged by increasing number of protons, the atomic number. Elements in the same column share similar chemical properties.
What is a molecule?
A combination of atoms
Define a chemical bond?
A form of attraction between atoms that hold them together
What are valence electrons?
Electrons located at the highest energy level. Responsible for chemical bonding
What is a molecular orbital?
A merged orbital between two electrons
Define covalent bond
It is the sharing of electrons to form a molecular orbital
What is a polar covalent bond?
The unequal sharing of electrons. Occurs due to differences in the electro negativity of atoms
Define electro negativity?
Increases along the periodic table
As the number of protons increases electrons are held more tightly to the nucleus therefore less likely to transfer an electron
What is a hydrogen bond?
Occurs when a H atom is covalently bonded to an electronegative atom (oxygen or nitrogen) interacts with an electronegative atom of another molecule
Weaker than covalent bonds
What are ionic bonds?
Bond between two ions
Na+ and Cl- form NaCl
What’s a polar molecule?
A molecule that has a + and a - regions
Define hydrophilic?
Water loving
Define hydrophobic?
Water fearing
What is the hydrophobic effect?
Polar molecules exclude non polar ones.
Example cell membrane
When does a neutral PH occur?
When does a acidic PH occur?
When does a basic PH occur?
Neutral PH occurs when H+ = OH-
Acidic PH occurs when H+ is greater than OH-
Basic PH occurs when H+ is less than OH-
Why is ice less dense than water?
When water freezes the molecules bond with four other molecules into a crystal lattice structure. Making ice less dense
Define cohesive force?
Tendency to stick together
What is surface tension?
Contrastive tendency of the surface of a liquid to resist an external force
What is an element?
A pure substance that cannot be broken down further by chemistry
What is an organic molecule?
A molecule that contains carbon
Forms tetrahedrons
Ability to rotate around a single bond. Cannot rotate around a double or triple bond
Define isomer?
Give an example
Molecules that have the same chemical formulae but have different structures.
Lucine and isoleucine
What do proteins do?
Provide structural support and act as catalysts during chemical reactions
What is the role of nuclei acids?
Encode and transmit genetic information
What is the role of carbohydrates?
Provide energy
Makes up cell wall in plants, bacteria and algae
What is the purpose of lipids?
Store energy
Make cell membranes
Act as a signalling molecule
What is a polymer?
What are the four main examples?
Complex molecules made up of repeated simpler units connected by covalent bonds Amino acids make up proteins Sugars make up carbohydrates Fatty acids make up lipids Nucleotides make up nucleic acid
What is an enzyme?
Protein based catalysts that accelerates the rate of chemical reactions
Describe a peptide bond
Links amino acids by the C atom of the carboxyl group to the N atom of the amino group
What is DNA?
The genetic material in all organisms
What’s is RNA?
Key player in protein synthesis and regulation of gene expression
What is a phosphodiester bond?
Joins adjacent pair of nucleotides using a phosphate group
Explain a double helix
Two strands of nucleotides twisted around each other
Define saccharides
Simplest form of sugars
Form in linear or cyclic molecules
What is the composition of sugars and what is the ratio?
Composed of C H O in a 1:2:1 ratio
What is a monosaccharide, disaccharide, polysaccharide?
One simple sugar, two simple sugars linked by covalent bonds, combination of simple sugars
What is a complex carbohydrates?
Long branched chains of monosaccharides
Define aldoses
Monosaccharides with an attached aldehyde group
Define ketoses
Monosaccharides with an attached ketone group
What are glycosidic bonds?
Covalent bonds that attach monosaccharides
Define triacylglycerol
Lipid used for energy storage
Made up of three fatty acids joined to glycerol
Define saturated fat
Fatty acids that do not contain a double bond
Define unsaturated fat
Fatty acids that contain a C-C double bond
Why are the kinks found in a fatty acid chain important?
Reduce tightness and therefore lower the melting point
Describe van der waal forces
Temporarily polarized molecules weakly bonded to one another due to the attraction of opposite forces
Define steroids
Second type of lipids
Example cholesterol
Define phospholipids
Third type of fatty acids major component of cell membranes
Describe the Stanley miller experiment
Water vapour, ammonia, methane and hydrogen gas and collected. A spark is introduced and the formation of 20 amino acids is the result
Know difference between RNA and DNA chemical structure
Ok
Be able to identify nucleic acids
Ok
Identify a phosphodiester bond
Ok
Know the three types of carbohydrate molecules
Ok
How are amino acids joined in a protein?
By a peptide bond
Recognize a fatty acid molecule
Ok
