Structure of Atoms
color change, temperature change, gas formation, or precipitate (solid) formation is often observed when a new substance(s) is formed
What is evidence of a chemical reaction
Outermost electrons in the electron cloud
What is Valence Electrons
New substances has different properties from the original substance
What is chemical reaction
Part of an atom surrounding the nucleus; consists mostly of empty space in which electrons move.
What is an electron cloud/energy levels
Determines the identity of an element; this number also equals the number of electrons in a neutral atom
What is atomic number
Reactions that absorb heat
What is endothermic