Chapter Two: Basic Chemistry Flashcards
Elements
A substance that cannot be broken down into simpler substances with different properties by ordinary chemical means
Atoms
The smallest part of an element that displays the properties of the element
Matter
Anything that take up space and has mass
Atomic symbol
One or two letter which stand for elements
Protons
Positive subatomic particle located in the nucleus and assigned one atomic mass unit
Neutrons
Neutral subatomic particle located in the nucleus and assigned one atomic mass unit
Electron
Negative subatomic particle, moving about in an energy level around the nucleus of an atom
Electron she’ll
The average location or energy level of an electron in an atom. Often drawn as concentric circles around the nucleus
Atomic number
Number of protons within the nucleus of atom
Mass number
Mass of an atom equal to the number of protons plus the number of neutrons within the nucleus
Atomic mass
Average of atom mass units for all the isotopes of an atom
Isotopes
Atoms of the same element that differ in the number of neutrons
Tracer
Detects molecular changes when a small amount of radioactive isotopes are added to a sample
Octet Rule
The observation that an atom is most stable when it’s outer shell is complete and contains eight electrons
Molecule
Exists when two or more elements bond together and is the smallest part of a compound that retains its chemical properties
Compound
A molecule containing at least two different elements
Formula
Tells the number of each kind of atom in a molecule
Ions
Charged particle that carries a negative of positive charge
Ionic bond
Chemical bond in which ions are attracted to one another by opposite charges
Salts
Solid substances that usually separate and exist as individual ions in water
Covalent bond
Results when two atoms share electrons in such a way that each atom has an octet of electrons in the outer shell
Nonpolar covalent bond
When the sharing of electrons between two atoms is equal
Electronegativity
Dependent on the number of protons- greater number of protons, greater electronegativity
Polar covalent bond
When electrons are not shared equally in a covalent bond
Hydrogen bond
A weak attraction between a slightly positive hydrogen atom and a slightly negative atom
Calorie
The amount of heat energy needed to raise the temperature of 1 gram of water 1 degree Celsius
Solution
Fluid that contains a dissolve liquid
Solute
Substance that is dissolved in a solvent
Hydrophilic
Molecules that do dissolve in water
Hydrophobic
Molecules that do not dissolve in water
Surface tension
Strong force between molecules in a liquid
Hydrogen ions
Hydrogen atom that has lost its electron and therefore has a positive charge
Hydroxide ions
One of two ions that results when a water molecule dissociates; gained an electron and therefore beard a negative charge
Acids
Molecules tending to raise the hydrogen ion concentration in a solution and thus to lower its pH numerically
Bases
Molecules tending to lower the hydrogen ion concentration in a solution and this raise the pH numerically
PH scale
Measurement scale for hydrogen in concentration
Buffer
Substance or group of substances that tend to resist pH changes of a solution, this stabilizing its relative acidity and basicity
What 6 elements make up 95% of the body weight of organisms
Hydrogen Nitrogen Carbon Oxygen Calcium Phosphorus
All isotopes have the same number of…
Protons
What type of bond is formed when atoms share electrons
Covalent
The three isotopes of carbon have different numbers of…
Neutrons
Which bond is most easily broken?
Hydrogen bond
Normal rainfall has a pH of…
8.3
Hydrophobic molecules tend to be…
Nonpolar
5 properties of water
High heat capacity High heat of evaporation Solvent Cohesive and Adhesive Ice is less dense than liquid water
Alkaline
Blood at a pH level of 7.4 (slightly basic)
Atom in Greek means…
Uncut or indivisible
The atom most commonly found in the human body is…
Oxygen
