Chapter 2 Flashcards
Protons
Positive charged particles
Neutrons
Neutral particles
Electrons
Negative charged particles
Atomic number
Number of protons
Same atomic number is same element
Atomic mass
Sum of protons and neutrons (1 Dalton)
Ions
Charged particles
Cations
Positively charged (more protons)
Anions
Negatively charged (more electrons)
Isotopes
Atoms of a single element with different number of neutrons
Radioactive isotopes
Unstable and emit radiation as nucleus breaks up
Electron number and arrangement
Dictates chemical behavior of an atom
Bohr model
Electrons in discrete orbits
Electrons potential energy
Close to nucleus, less potential energy
Further from nucleus, more potential energy
Oxidation
Loss of electron
Reduction
Gain an electron
OIL RIG
Oxidation Is Loss
Reduction Is Gain
Redox
Process of reduction and oxidation
Valence electrons
Number of electrons in outermost energy level
Inert elements (nonreactive)
Elements have all 8 electrons
Octet rule
Atoms tend to establish completely full outer energy levels, those that are not filled are less reactive than those that are unfilled
Organic molecules (96.3%of human body weight)
Carbon, Hydrogen, Oxygen, Nitrogen
Molecules
1 type of element. Groups of 2 or more atoms that are held together in stable association
Compounds
Molecules containing more than 1 type of element
Chemical bonds
How atoms are held together in molecules and compounds
Ionic Bonds
Formed by the attraction of oppositely charged ions. (Gain or loss of electrons forms ions)
Covalent bonds
Form when atoms share 2 or more valence electrons. Strength determined by number of electrons shared.
Electronegativity
An atom’s affinity for electrons
Nonpolar covalent bonds
Equal sharing of electrons. 50/50
Polar covalent bonds
Unequal sharing of electrons.
One side slightly more negative (more of electrons) Other side slightly more positive.
Chemical Reactions
Formation or breaking of chemical bonds
Temperature
Concentration of reactants and products
Availability of a catalyst (Enzymes - proteins or RNA)
Hydrogen Bonds
Weak individual attractions between the partially neg O of one water molecule and partially pos H of a different water molecule. O partially neg, H partially pos.Highly polar. Can be between water molecules or another charged molecule
Cohesion
Water molecules stick to other water molecules by hydrogen bonding. Weak individually but cumulative effects are strong.
Adhesion
Water molecules stick to other polar molecules by hydrogen bonding
Solvent
Desolves molecules and ions
Hydrophilic
Water loving
Hydrophobic
Water fearing
pH
Hydrogen ion (H+¹) is the basis of scale. Negative logarithm of hydrogen ion concentration of a solution
Greater H+¹ concentration = Lower pH (acidic)
Lower H+¹ concentration = higher pH (basic)
Acid
Chemical that releases H+¹ ions. Stronger an acid is the more hydrogen ions it produces and the lower its pH
Base
Chemical that accepts H+¹ ions.
Buffer
Substance that resists changes in pH (ex. water). Releasing hydrogen ions when a base is added. Absorbing hydrogen ions when acid is added
