Bio-110 Chapter 2 Lecture Flashcards
What are Elements?
Substances composed of a single type of atom that cannot be broken down chemically
Atoms are made up of protons, neutrons, and electrons, but for this context, Element and Atom are interchangeable.
What is an atom
Smaller particles that are made up of protons, neutrons, electrons
Protons carry a positive charge, while neutrons carry no charge.
Structure of an atom
- protons & carry positive charge, in the nucleus
- neutrons & no charge, in the nucleus
- electrons & carry negative charge, outside the nucleus
What is the Atomic Mass?
The total weight of Protons and Neutrons in an atom
For example, Oxygen has 8 protons and 8 neutrons, giving it an approximate Atomic Mass of 16.
What does the Periodic Table represent?
A grouping of atoms/elements by their characteristics, organized by Atomic Number
It contains 118 Elements, of which 92 are found in nature.
What is the smallest atom?
Hydrogen
It has one proton in the nucleus and one electron revolving around it.
What is the significance of Electron Shells?
They surround the nucleus of an atom and contain electrons
Oxygen has 8 electrons with 2 in the inner shell and 6 in the second shell.
What characterizes unstable atoms?
They do not have 8 electrons in their outer shells
Unstable atoms react with others to achieve stability.
What are Isotopes?
Different versions of an atom due to variations in the number of Neutrons
Carbon has three isotopes: Carbon 12, Carbon 13, and Carbon 14.
What are Radioactive Atoms?
Atoms with unstable nuclei that break down spontaneously, releasing energy
This can be useful in determining the age of fossils and in medical applications.
What are Ions?
Atoms that have lost or gained electrons
Positive ions have an extra positive charge, while negative ions carry an extra negative charge.
What is Octet’s Rule?
The tendency of atoms to prefer having 8 electrons in their outer shell
This drives chemical reactions, including ionic and covalent interactions.
What are the three types of chemical bonds?
Ionic bonds, Covalent bonds, and Polar Covalent bonds
Each type involves different interactions between atoms.
What is an Ionic Bond?
A bond formed when electrons are lost or gained, leading to the attraction between oppositely charged ions
Table salt (NaCl) is a common example.
What is a Covalent Bond?
A bond formed by the sharing of electrons between atoms
Water is a classic example of a molecule formed by covalent bonds.
Define Polar Covalent Bonds.
Bonds where electrons are shared unequally, creating a molecule with a slight charge difference
Water is the most important example of a polar covalent bond.
What are Hydrogen Bonds?
Weak attractions between the negative side of one water molecule and the positive side of another
These bonds allow water to remain liquid at room temperature.
How do temperature, pH, and concentration affect chemical reactions?
They influence reaction rates by affecting atom movement and enzyme activity
Higher temperatures speed up reactions, while extreme pH levels can inhibit enzymes.
What type of bonds are very important to living organisms?
Hydrogen Bonds
Hydrogen bonds are attractive forces between the negative Oxygen side of one water molecule to the positive Hydrogen side of another water molecule.
What is the nature of hydrogen bonds compared to ionic bonds?
Hydrogen bonds are relatively weak and can be broken very easily
In contrast, ionic bonds involve strong bond attractions between ions.
Why does water remain a liquid at room temperature?
Due to the constant breaking and reforming of hydrogen bonds
These weak attractions allow water to flow and move within living organisms.
What would happen if water could not form hydrogen bonds?
It would boil at -80° C and freeze at -100° C
Such temperatures are not conducive to living organisms.
What are the five most important properties of water?
- Cohesion
- Surface Tension
- High Heat Capacity
- Less Dense as Ice
- Solvent of Life
What property of water allows it to flow in tubes found in living organisms?
Cohesion
Cohesion is the ability of water molecules to stick together due to hydrogen bonds.
