Chemistry Flashcards
What 3 forms does matter exist in
Solid
Liquid
Gas
What is an element
Pure substance that can not be chemically broken down
What is an atom
The smallest particle of an element that still retains its chemical properties
What 12 elements occur in large amounts? Most common elements is humans
Major elements
Oxygen, carbon, hydrogen, nitrogen, calcium, phosphorus
Minor elements
Sulfur, potassium, sodium, chlorine, magnesium, iron
Atom structure
Atomic nucleus contains two subatomic particles
1 protons carry positive charge +
2 neutrons uncharged
Electrons negatively charged
Move around the nucleus
Atomic number
Number of protons unique to each atom
Mass number
Number of protons and neutrons
Isotope
Number of protons does not equal number of neutrons
Uses of isotopes
PET scan
Positron-emission tomography
Chemical compound
Stable association between two or more elements combined in a fixed ratio
Electrons
Attracted to the positive nucleus
Moves in orbitals, area around the nucleus
Valence
Outermost shell
Octet rule
Atoms gain lose or share electrons to fill the outermost she’ll
No reactive atoms
Atoms that naturally occur with a full outermost shell Called inert do not undergo reactions
Examples helium, neon, argon
Chemical bonds three types
Ionic bond
Covalent bond strongest
Hydrogen bond weakest
Ion
Atoms that have lost or gained one or more electrons
Number of protons differs from the number of electrons
Have an electric charge + or -
Common human ions sodium, potassium, chloride
Cation
Positively charged ion
Anion
Negatively charged ion
Electronegativity
Measure of an atoms attractiveness to electrons
- depends on atoms size and number of protons
Creates a positive cation from a negative anion
Opposite charged ions are attracted creating ionic bonds
Covalent bonds
Bonds that forms when atoms share electrons
Nonpolar covalent bonds
Two identical atoms share electrons equally
Nuclei of the atoms have the same number of protons
Polar covalent bonds
Occurs between atoms of different elements
- have different numbers of protons and different electronegativities
Hydrogen bonds
Weak attraction between opposite charges on adjacent polar covalent molecules
Example water
Functions of water in humans
Transports
Lubricates
Cushions
Excretes wastes
Properties of water
Cohesion and adhesion
Cohesion
Attraction between two polar water molecules due to hydrogen bonds
Adhesion
Attraction between water and another polar molecule
Properties of water:solvent
Ions and polar molecules dissolve easily in water (solutes)
Called hydrophilic water loving
Examples glucose, alcohol, salt
Substances that do not dissolve in water
Water repels nonpolar molecules called hydrophobic
Example oil
Water ionization
Equal number of ions created so water is neutral
pH
Expression of the hydrogen ion concentration of a solution
Change in one on the pH scale is a change in 10 of hydrogen ion concentration
Acid and base
Substance that increases the concentration of H+ when dissolved in water
- pH 0-6.99 acid
Substance that combines with H+ when dissolved in water
- lowers the H+ concentration
- pH 7.01-14
Cell pH
Fairly close to 7
Chemical reactions constantly produce acids and bases
We consume foods that are acidic and basic
How do cells maintain a constant pH
Buffer
Substance that can take up or release H+ in a solution as the H+ concentration changes
Pair of substance one acid and one basic
Bicarbonate buffer
When blood pH rises carbonic acid dissociates to form bicarbonate and H+
When blood pH drops bicarbonate binds H+ to form carbonic acid
What are all living things made up of?
Matter
Has mass
Occupies space
