Chemical Basis Of Life Flashcards
What is an element?
Unique substance that cannot be broken down by ordinary chemical means, listed on periodic table
What are the major elements of the human body?
Oxygen, carbon, hydrogen, nitrogen
What is an isotope?
Atoms with the same number of protons but a different number of neutrons
What are the three types of chemical bonds?
Covalent, ionic, and hydrogen bonds (hydrogen bonds are just a strong attraction)
How are covalent bonds formed?
By the sharing of two or more electrons
How are ionic bonds formed?
By the transfer of one or more electrons between atoms, resulting in a charge
What is a molecule?
Two or more atoms held together by covalent bonds to form a structure that behaves as an independent unit
What is a compound?
Two or more different kinds of atoms chemically combined
What are the properties of water?
- solvency
- cohesion and adhesion
- high surface tension
- high heat capacity
- high heat of vaporization
- varying density
What is cohesion?
Ability of water molecules to cling to each other due to hydrogen bonding
What is adhesion
Ability of water molecules to cling to other polar surfaces
Why does water have high heat capacity?
The hydrogen bonds between water molecules absorb heat without greatly changing its temperature
Is water less or more dense than ice, why?
Less, the water molecules in ice are farther apart than in water
What ion does an acid have more of? Where on the pH scale do acids fall?
More H+ ( hydrogen) ions, below 7 on the pH scale is an acid
What ion do bases have more of? Where on the pH scale so bases fall?
Bases have more OH- (hydroxide) ions, they are above 7 on the pH scale.
