Chapter 2- Chemistry Flashcards
What is matter composed of?
atoms
Why do atoms combine?
To form compounds and molecules
How do atoms interact?
Through electrons
Strength of molecular interactions
Can be either strong or weak
What fundamental substances is the natural world composed of?
Elements
substances that can’t be broken down by a chemical reaction
Elements
How are elements identified on period table?
Chemical symbols
What elements make up ~96% of matter in organisms?
-Oxygen
-Carbon
-Hydrogen
-Nitrogen
What are compounds made of?
Compounds contain 2+ different elements
What contains
-Protons
-Electrons
-Neutrons
Atoms
Protons are?
Positive charge
Neutrons are?
neutral, no charge
Electrons are?
negative charge
How are elements identified by?
the number of protons in an atom
What is the atomic number?
Number of protons
What charge are atoms overall?
They are neutral, no charge
What does the number of electrons equal to?
Usually equals the number of protons
Where are electrons found?
In the shells
How many electrons go in shell 1?
2
How many electrons in shell 2?
8
How many electrons in shell 3?
8
What happens to the energy the closer electrons get to the nucleus?
The energy lowers
Where do all chemical interactions in atoms occur?
Between electrons ONLY
(nuclei never interact)
Even though protons are the same, electrons are
NOT the same
(variable amounts of energy)
What is the outer electron shell called?
Valence shell
What are the electrons in the valence shell called?
valence electrons
When are atoms most stable?
When the valence shell is full
Attractions are the result of what?
interactions between valence electrons of 2+ atoms
The strength of chemicals bonds can be?
strong or weak
extremely strong and stable bonds
Covalent bonds
When do covalent bonds occur?
when adjacent atoms share electrons
When 2 or more atoms are held together by covalent bonds
Molecule
Why are atoms “bullies”?
They don’t always share their electrons equally
measure of how nucleus holds onto electrons
EN
The more EN
the more strongly it pulls electrons
Which are the most EN atoms of biological importance?
Oxygen and Nitrogen
electrons are shared equally and charge are distributed symmetrically
Nonpolar covalent bond
Unequal electron sharing and asymmetric distribution of electron charges
Polar covalent bonds
What do weak bonds result from?
electrostatic attractions between two atoms
Types of Weak bonds
-Hydrogen bonds
-Ionic bonds
-van deer Waal interaction
-Extremely important in biological systems
-occurs when H covalently bonded to one EN attracted to another EN atom
hydrogen bonds
large EN differences pull electrons from the outer shell of one atoms
Ionic bonds
atoms with electrical charge
(positive or negative)
Ions
How do atoms become ions?
gaining or losing electrons
attractions between molecules that are close together as result of temporary changes (extremely weak)
Van der Waals interaction
What do van der Waals interactions determine?
-3D shape of proteins
-Specific interactions of antigens and antibodies
-Specific interactions between enzymes and substrate
Van der Waals:
If electrons are not evenly distributed
They may accumulate by chance in one part of the molecule
