LO 2 Flashcards
Chemicals are in the form of ______ which are composed of ________
Molecules, atoms
Regions surrounding the atoms nucleus and contain electrons are called _________
Energy levels (orbitals)
What determines the atomic number of an element?
The number of protons
What determines the atomic mass of an element?
Number of protons and neutrons
How many electrons may be contained in each orbital?
2 in the first, 8 in all following
Energy of electrons increases with ________
Distance from the nucleus
Define element
A pure substance made of only one kind of atom
Define molecule
A group of atoms bound together to form a larger chemical unit - e.g. H2O
Define compound
Substances whose molecules have more than one kind of atom
Living organisms require about ____ elements
20
Which 4 elements are most abundant in the human body?
Oxygen, carbon, hydrogen, and nitrogen - about 96% of body weight
Ionic bonds form between atoms that have ____ electrons in their outer shell and atoms that have _____ electrons in their outer shell
1 or 2; 6 or 7
Define ion
Atom or group of atoms with a positive or negative electric charge
Ionic bonds form when _____ attracts each other
A positive and negative ion (donation of electrons leave them with similar opposite charges)
Define electrolyte
Ionic molecules usually dissolved in water and dissociate to form free ions
Do covalent bonds dissociate in water?
No, because they share electrons they are closer together
Define hydrogen bond
A relatively weak electrostatic force of attraction between hydrogen atom and a more electronegative doner atom or group
Define organic compounds
Contain carbon-carbon covalent bonds and/or carbon-hydrogen covalent bonds
Define inorganic compounds
Do not contain the carbon-carbon or carbon-hydrogen bonds found in organic compounds
The most abundant solvent is ______
Water
Define solvent
A liquid into which solutes are dissolved, that forms an aqueous solution
Define dehydration synthesis
Water is removed from small molecules so they can be strung together to form a larger molecule (e.g. formation of bio molecules from monomers)
Define hydrolysis
Water is added to the subunits of a large molecule to break it into smaller molecules (e.g. bio molecules breaking down into monomers)
_______ is either stored or released in every chemical reaction
Energy
