Vocabulary ATOM-the smallest unit that maintains the characteristics of an element – Nucleus- The center of the atom, contains protons and neutrons – Electron Cloud –Region surrounding the nucleus containing the electrons
The Nucleus Proton-A positively charged sub-atomic particle (+). Atomic Mass=1 amu The number of protons is the same as the atomic number Li 3 7 The atomic mass The Atomic Symbol
The Nucleus Neutrons –A sub-atomic particle in the nucleus --Has a mass equal to 1 atomic mass unit --Neutron do not have a charge (0) To calculate the number of neutrons in an element… Li 3 7 The atomic number The atomic mass -The atomic number The number of neutrons
Li 3 7 The atomic number The atomic mass 7 (Atomic Mass) -3 protons(Atomic #) 4 neutrons
WRITING RESPONSE How many protons does Mg have? How many neutrons does Mg Have?
WRITING RESPONSE How many protons does Mg have?12 How many neutrons does Mg Have? 12
The Electron Cloud Electrons- The number of electrons equals the number of protons Sub-atomic particle with a negative charge (-) Electrons behave as if in a 3-D orbit Valence Electrons – The outer most electrons – Valence electrons are responsible for bonding
WRITING RESPONSE How many protons? How many neutrons? How many electrons?
WRITING RESPONSE How many protons? 3 How many neutrons? 4 How many electrons? 3
IONS Charged particles that occur when an atom gains or loses an electron during chemical bonding. If the atom gains an electron- Negative charge Ex: Cl - Most non-metals form negative Ions If the atom loses an electron- Positive Charge Ex: Na + Most metals form Positive Ions
Losing an Electron = Positive ion Na + has 11 protons but only 10 electrons Gaining an Electron = Negative ion Cl - has 17 protons but has 18 electrons
What would the charge be on an atom that lost an electron? Gained two electrons?
Which shows a negative ion? Explain Which shows a neutral atom? Explain Which shows a positive atom? Explain A B C