Ch. 2 The nature of molecules & the properties of water Flashcards
What type of bond allows water to “stick” to other surfaces/associate with other molecules?
Hydrogen bond
What’s matter?
Anything that has mass and takes up space; composed of atoms
What did Rutherford’s scatter experiment discover?
The existence of the nucleus
What did Neils Bohr propose?
The Bohr model which states that every atom has an orbiting cloud of electrons whizzing around a dense nucleus formed by protons and neutrons
What’s an atomic number?
the number of protons in the nucleus of an atom
What’s an element?
Simplest form of chemical matter, cannot be broken further
What charge do protons have?
Positive
What charge do neutrons have?
Neutral (no charge)
What charge do electrons have?
Negative
Which element has no neutrons?
Hydrogen
What’s mass?
the amount of matter in an object
What’s weight?
the force of gravity acting on an object
What does the atomic mass of an atom equal?
The sum of the masses of its protons and neutrons
What’s a dalton?
unit of measurement for the mass of atoms and subatomic particles
What’s a neutral atom?
Atom that has equal amount of protons and electrons
What’s an ion?
an atom with an unequal number of protons and electrons which results in charged particles
What’s an isotope?
Atoms of the same element that have different numbers of neutrons
What’s radioactive decay?
When an unstable isotope’s nucleus breaks up
What’s a half-life?
time it takes one half of the atoms in a sample to decay (usually a constant rate)
What’s the main issue with the Bohr model?
Not accurate in terms of reality as electrons can be anywhere and not in a circle around the nucleus
What’s an orbital?
A three-dimensional region around the nucleus that indicates the probable location of an electron
How many electrons can be in the first orbital?
no more than 2
What makes up the volume of an atom?
empty space
What determines the chemical behavior of an atom?
The distribution of electrons in the atoms electron shells
Define energy
the ability to do work
Moving an electron away from the nucleus ______ potential but ________ if moved closer.
increases, decreases
What’s a redox reaction?
when reduction and oxidation happen at the same time
Who created the periodic table of elements?
Dmitri Mendeleev
What are valence electrons?
Electrons on the outermost energy level of an atom
What electrons are known to be the basis for differing chemical properties of elements?
valence electrons
What is the octet rule?
Atoms tend to gain, lose or share electrons in order to have a full set of valance electrons.
What are organic compounds made of (abbreviation only)
OCHN
What’s the most common molecule in the human body?
Water
What’s the most abundant element in the human body?
oxygen
What’s a compound?
a molecule with atoms of more than one element
What are chemical bonds?
where atoms in molecules are bonded
What are ionic bonds?
atoms that have gained or lost electrons and become charged
What are covalent bonds?
Are atoms that are sharing a pair or more of valence electrons.
What’s a hydrogen bond?
a weak bond between two partially charged atoms occurs between a hydrogen atom and another atom that is more electronegative (such as nitrogen and oxygen)
What’s a hydrophobic interaction?
forcing of hydrophobic portions of a molecule together in presence of polar substances
What’s hydrophobic mean?
Fear of water
What’s hydrophilic mean?
Water loving
What’s a van der waals attraction?
weak attractions between atoms due to opposite polarized electron clouds
Why is a molecule formed by 2 hydrogen atoms stable? (hint there are 3 answers)
1) has no net charge
2) octet rule is satisfied
3) has no unpaired electrons
What are double bonds?
when atoms share two pairs of electrons
What are single bonds?
when two atoms share a single pair of electrons
What’s a non-polar bond?
a covalent bond in which electrons are shared equally
What is a polar covalent bond?
unequal sharing of electrons
What’s a chemical reaction?
formation or breaking of chemical bonds
What’s a reactant?
a substance present at the start of a reaction
What’s a product?
What’s produced at the end of a chemical reaction
What are the 3 things that influence chemical reactions?
1) temperature
2) concentration of reactants and products
3) catalysts
What’s a catalyst?
substance that speeds up the rate of a chemical reaction
What’s adhesion?
attraction between molecules of different substances
What is temperature?
the result of how fast individual molecules are moving
What’s specific heat?
the heat required to raise the temperature of the unit mass of a given substance by a given amount
What is heat of vaporization?
the heat a liquid must absorb for 1 g to be converted to gas
What’s hydrophobic exclusion?
tendency of non polar molecules to aggregate in water
What’s ionization?
a process when a molecule acquires a negative or positive charge based on how many electrons said molecule gains or loses
What’s a mole?
weight of a substance in grams that corresponds to the atomic masses of all of the atoms in a single molecule of that substance
What does pH stand for?
power of hydrogen
What is acid?
any compound that forms H+ ions in solution
What is basic?
solutions with a pH above 7 because they have more OH- ions
What’s a buffer?
a solution that resists change in pH
What does OH- stand for?
Hydroxide
What does [H+] mean?
concentration of hydrogen ions
What is the order (from strongest to weakest) of the bonds and their interactions?
1) covalent
2) ionic
3) hydrogen
4) hydrophobic
5) van der Waals
What’s a solvent?
The substance that dissolves the solute and makes a solution.
