The small unit of matter that retains the properties of an element.
What is an atom?
100
An attraction between two atoms resulting from a sharing of outer-shell electrons or the presence of opposite charges on the atoms. The bonded atoms gain complete outer electron shells.
What is a chemical bond?
100
A type of weak chemical bond formed when the partially positive hydrogen atom participating in a polar covalent bond in one molecule is attracted to the partially negative atom participating in a polar covalent bond in another molecule (or in another part of the same macromolecule).
What is a hydrogen bond?
100
These elements make up 96% of the human body weight.
What are Carbon, Hydrogen, Nitrogen, and Oxygen (CHON)?
200
A substance that increases the hydrogen ion concentration in a solution
What is acid?
200
The making and breaking of chemical bonds, leading to changes in the composition of matter.
What is a chemical reaction?
200
Daily Double
A measure of the relative acidity of a solution, ranging in value from 0 (most acidic) to 14 (most basic). The letters pH stand for potential hydrogen and refer to the concentration of hydrogen ions (H).
ǝlɐɔs Hd
200
A substance that cannot be broken down to other substances by ordinary chemical means.
What is an element?
300
The attraction between different kinds of molecules.
What is adhesion?
300
An attraction between atoms that share one or more pairs of outer-shell electrons; symbolized by a single line between the atoms.
What is a covalent bond?
300
A measure of how difficult it is to stretch or break the surface of a liquid.
What is surface tension?
300
A substance containing two or more elements in a fixed ratio. For example, table salt (NaCl) consists of one atom of the element sodium (Na) for every atom of chlorine (Cl).
What is a compound?
400
A solution in which water is the solvent.
What is aqueous solution?
400
A chemical bond resulting from the attraction between oppositely charged ions.
What is an ionic bond?
400
The process in which the surface of an object become cooler during evaporation.
What is evaporative cooling?
400
Today chemists recognize this many elements that occur in nature.
What is 92 elements?
500
The number of protons in each atom of a particular element.
What is the atomic number?
500
Daily Double
An energy level representing the distance of an electron from the nucleus of an atom.
llǝɥs uoɹʇɔǝlǝ
500
The binding together of like molecules, often by hydrogen bonds.
What is cohesion?
500
This element makes up 1.5% of the human body weight.