Areas in an Atom NUCLEUS: positively charged center of an atom containing almost all the atomic mass ELECTRON CLOUD: negatively charged area around the nucleus with almost no mass Atomic Particles PROTON: positively charged particle in the nucleus, has mass (1 AMU)* ELECTRON: negatively charged particle in the electron cloud, no mass NEUTRON: neutral (no charge) particle in the nucleus, has mass (1 AMU)* *AMU: Atomic Mass Unit The charge of a proton (p+) is EQUAL and OPPOSITE to the charge of an electron (e-). In ALL ATOMS the number of protons equals the number of electrons. ATOMS HAVE NO OVERALL ELECTRICAL CHARGE. Elements are different because they have different numbers of protons and electrons than other elements. ATOMIC NUMBER: the number of protons (or electrons) in one atom of an element Atomic Number = # p+ = #e- ATOMIC MASS NUMBER: the number of protons PLUS the number of neutrons in an atom of an element Atomic Mass Number = # p+ + # n # n = Atomic Mass Number - # p+ Always round the Atomic Mass to the nearest whole number.
Areas in an Atom NUCLEUS: positively charged center of an atom containing almost all the atomic mass ELECTRON CLOUD: negatively charged area around the nucleus with almost no mass Atomic Particles PROTON: positively charged particle in the nucleus, has mass (1 AMU)* ELECTRON: negatively charged particle in the electron cloud, no mass NEUTRON: neutral (no charge) particle in the nucleus, has mass (1 AMU)* *AMU: Atomic Mass Unit The charge of a proton (p+) is EQUAL and OPPOSITE to the charge of an electron (e-). In ALL ATOMS the number of protons equals the number of electrons. ATOMS HAVE NO OVERALL ELECTRICAL CHARGE. Elements are different because they have different numbers of protons and electrons than other elements. ATOMIC NUMBER: the number of protons (or electrons) in one atom of an element Atomic Number = # p+ = #e- ATOMIC MASS NUMBER: the number of protons PLUS the number of neutrons in an atom of an element Atomic Mass Number = # p+ + # n # n = Atomic Mass Number - # p+ Always round the Atomic Mass to the nearest whole number.