Chapter 2 - Molecules of Life Flashcards
What are the 5 bases? (for Bio)
Cytosine, Thymine, Uracil, Guanine, Adenine
What are the 3 pyrimidines?
Cytosine, Thymine, Uracil
What are the 2 purines?
Guanine, Adenine
What are the 4 bases in DNA?
Cytosine, Thymine, Guanine, Adenine
What are the 4 bases in RNA?
Cytosine, Uracil, Guanine, Adenine
What are the base pairings?
Cytosine pairs with Guanine, Thymine (or Uracil in RNA) pairs with Adenine
What are the parts of the atom?
a dense central nucleus made up of positively charge protons and neutral particles neutrons. negatively charged electrons move around the nucleus at some distance.
What is the number of protons called?
atomic number
What is the atomic mass determined by?
the number of protons and neutrons together
What is the mass of protons considered to be?
1
WHat is the mass of neutrons considered to be?
1
WHat is the mass of electrons considered to be?
negligible
What are Isotopes?
atoms of the same element that have different numbers of neutrons
What is the charge of most atoms?
neutral
What is an ion?
when the atom is charged (has lost or gained electrons)
Where do electrons occupy?
space called orbitals
What is an orbital?
where an electron is present most of the time - the exact location at any point is unpredictable
WHat is the maximum number of electrons in an orbital?
2 (most atoms have several orbitals)
WHat is the difference between electrons close to nucleus and further away from nucleus?
electrons close to the nucleus have less energy than electrons in orbitals further away
WHo developed the periodic table?
Dmitri Mendeleev
What is a horizontal row in the periodic table called?
period (first 3 rows have the same number of shells)
What is a vertical column in the periodic table called?
group (same number of electrons in outer shell)
What is a molecule?
2 or more atoms attached together that act as a single unit
What is a chemical bond?
a form of attraction between atoms that holds them together
What is a covalent bond?
when 2 atoms share electrons (1 from each orbital the orbitals merge and form 1 molecular orbital
What are electrons shared in a covalent bond from and called?
from the outermost orbitals called valance electrons
they are at the highest energy level of the atom
What is a covalent bond denoted by?
a single line
What is a double bond denoted by?
double parallel lines (when four orbitals merge to become 2)
When are molecules most stable?
when the outermost shell is full