Elements and Atoms: Building Blocks of Matter Flashcards
Matter
Anything that occupies space and has mass
Weight vs Mass
Mass - amount of matter contained in an object
Weight - an objects mass as affected by the pull of gravity
Element
A type of matter (pure substance) that cannot be created or broken down by ordinary chemical means (Carbon, Sulfur, Hydrogen, Oxygen, Nitrogen)
Compound
A substance composed of two or more (different) elements joined by chemical bonds. The elements that make up any given compound occur in the same relative amounts (ex. Glucose -> C6-H12-O6)
Atom
The smallest possible particle of an element that retains all of the properties of that element
Atomic Number
An atom of carbon is unique to carbon, but a proton of carbon is not. One proton is the same as another, whether it is in carbon, sodium, nitrogen (same for neutrons and electrons). The unique quantity of protons an element contains distinguishes it from other elements. No other element has exactly 6 protons in it’s atoms. Atomic number = number of protons.
Atomic Mass
Protons + Neutrons
Molecule
Two or more atoms chemically combined
Molecular Formula
A combination of symbols that indicates the number and type of atoms in a molecule (ex. H2O)
Structural Formula
Shows the arrangement of atoms/molecules
Valence Shell
An atom’s outermost electron shell. If the valence shell is full, the atom is stable and unlikely to be pulled away from the nucleus by the electrical charge of other atoms. If the valence shell isn’t full, the atom is reactive, meaning it will react with other atoms in ways that make the valence shell full.
Octet Rule
All atoms “want” to have a full outer shell which is 8 electrons (except for hydrogen and helium)
Bond
A weak or strong electrical attraction that holds atoms in the same vicinity
Ion
An atom that has an electrical charge - whether positive or negative.
Atoms typically have the same number of protons as electrons, however when an atom participates in a chemical reaction in order to have a full valence electron shell (octet rule) it’s number of protons and electrons will differ because it either donated or accepted electrons
Cation
A positively charged Ion
Ex. Potassium (K) has atomic number 19, just one electron in it’s valence shell. In chemical reactions it will lose an electron to have a full shell because that is easier than gaining 7. The loss of the negatively charged electron will cause the positively charged protons to be more influential than the remaining negatively charged electrons because there will be more protons than electrons. (K+)
Anion
A negatively charged Ion
Ex. Fluorine, atomic number 9, has 7 electrons in it’s valence shell. It is likely to bond with atoms in such a way that it gains one electron to have a full valence shell (octet rule) because that is easier than losing 7. When it does, it’s electrons will outnumber it’s protons by one, giving it an overall negative charge
Ionic Bond
An ongoing, close association between ions of opposite charge.
The opposite charges of cations and anions exert a moderately strong mutual connection that keeps atoms in close proximity forming an ionic bond. Ex. Sodium commonly donates an electron to chlorine, becoming Na+. When chlorine accepts the electron, it becomes Cl-. With their opposing charges, these two ions strongly attract each other (NaCl).
Electrolytes
Dissolved ions in a liquid state that produce electrical charges within the body
Covalent Bonds
Molecules formed by a covalent bond share electrons in a mutually stabilizing relationship
Electrons move back and forth between the elements. Because of the sharing of pairs of electrons (one electron from each of two atoms) covalent bonds are stronger than ionic bonds
Nonpolar Covalent Bonds
The sharing of the negative electrons between the atoms is relatively equal, as is the electrical pull of the positive protons in the nucleus of the atoms involved. That is why covalently bonded molecules that are electrically balanced in this way are described as non polar, that is, no region of the molecule is either more positive or more negative than any other
Polar Covalent Bonds
A molecule that contains regions that have opposite electrical charges. Polar molecules occur when atoms share electrons unequally.
Ex. Water (H2O) oxygen contains 8 protons and the two hydrogen atoms contain only 1. Because every proton exerts an identical positive charge, the nucleus that has 8 protons exerts a charge eight times greater than a nucleus that contains one proton. This means that the negatively charged electrons present in the water molecule are more strongly attracted to the oxygen nucleus than to the hydrogen nuclei. Each hydrogen atom’s single negative electron therefore migrated toward the oxygen atom, making the oxygen end of their bond slightly more negative than the hydrogen end of their bond
Hydrogen Bond
Formed when a weakly positive hydrogen atom already bonded to one electronegative atom is attracted to another electronegative atom from another molecule. Hydrogen bonds always include hydrogen that is already part of a polar molecule. Not an actual bond, an electrostatic attraction between two solar groups
Inorganic Compounds
A substance that does not contain both carbon and hydrogen
Organic Compound
A substance that contains both carbon and hydrogen