Chem

consists of a nucleus positively charged protons and neutrally charged neutrons. negatively charged electrons are arranged outside of the nucleus

groups of two or more atoms held together by chemical bonds

• ability of an atom to attract electrons
• 3 kinds of bonds: ionic, covalent, hydrogen

• bonds formed between two atoms when one or more electrons are transferred from one atom to the other. occur when electronegativity is very different and one atom has a much stronger pull.
• atom that gains electrons has a negative charge
• atom that loses electrons has a positive charge
• ex. Na+ Cl- = NaCl

• form when electrons between atoms are shared. occurs when electronegativities are similar.
• -nonpolar covalent bond
• -polar covalent bond

• bonds form when electrons are share equally. when the 2 atoms sharing electrons are identical
• ex. O2

bonds are formed when electrons are shared unequally. different electronegativities and an unequal distribution of the electrons results

weak bonds between molecules. form when a positively charged hydrogen atom in one covalently bonded molecule is attracted to a negatively charged area of another covalent bond