Chemical Bonds Flashcards
What is a chemical bond?
A weak or strong electrical attraction that holds atoms in the same vicinity
- atoms don’t actually touch in a chemical bond
- occurs when atoms are close enough for a valance shell electron to interact with another
What is a molecule?
A stable group of 2 or more atoms held together by chemical bonds
What is a compound?
A molecule made of 2 or more atoms of different elements
What are the 2 types of chemical bonds?
- Ionic Bonds
- Covalent Bonds
What are ions?
- when an atom participates in a chemical reaction resulting in giving or taking an electron it will become negatively or positively charged
- an atom that has an electrical charge, negative or positive, is an ion
What are positive ions?
After donating an electron, it has more protons than electrons causing it to be positively charged (cation)
What are negative ions?
After an atom gains an electron, it has more electrons than protons, resulting in a negatively charged ion (anion)
What are ionic bonds?
- ongoing association between ions of opposite charge
- keeps atoms in close proximity
- negative ions can donate electrons to positive ions, forming an ionic bond between ions
How do ions react in solution?
- Compounds that form from ionic bonding readily dissolve in water and create electrolytes
What are electrolytes
- dissolved ions
- create electrical charges in the body
- these create currents of charge movement across the plasma membrane
- this affects the voltage or potential in a cell (movement of ions through ion channels in cell membranes is the basis for membrane potentials in all cells and for creating action potentials in neurons)
What are covalent bonds?
- molecules that share electrons in a mutually stabilizing relationship
- most common chemical bond
- can be decomposed by enzymes
What are the 2 types of covalent bonds?
- polar covalent bonds
- non-polar covalent bonds
What is a single covalent bond?
ex. 1 hydrogen atom shares its single atom with another
What is a double covalent bond?
ex. oxygen atoms achieve stability by sharing 2 pairs of electrons
What are 2 double covalent bonds?
ex. one carbon atom and 2 oxygen atoms achieve stability by each sharing 2 pairs of electrons
What are the three types of non-polar covalent bonds?
Single, double, and 2 double covalent bonds
What are polar covalent bonds?
- a polar molecule is a molecule that contains regions that have opposite electrical charges that are partial/delta charges
- most common is H2O
- electrons are more attracted to 8 oxygen protons than 1 hydrogen proton
- this is why they have slightly positive and negative charges
What is a dipole?
A dipole has positive charges at one end that are formed by the hydrogen atoms at the bottom of the tent and negative charge at the opposite end at the top of the tent (oxygen atom)
- makes it highly likely for charge regions to interact with other charge regions of other polar molecules or dissolved ions in solution
What is a hydrogen bond?
- a bond between a weakly positive hydrogen atom that has already bonded to an electronegative atom
- they are relatively weak bonds
- folding of proteins into their structure depends on hydrogen bonds
What are hydrophilic interactions?
Water molecules attract polar molecules and ions
What are hydrophobic interactions?
Water molecules repel molecules with non-polar covalent bonds (fats, lipids, oils, steroid hormones)
- non-polar compounds clump together to minimize contact with water
- folding of proteins, phospholipid bilayers, the structure of cholesterol in the blood
What is the phospholipid bilayer?
- made up of many phospholipid molecules
- has a hydrophilic head and a hydrophobic tail
- makes up the plasma cell membrane and intracellular organelle membranes
