Do Now 26 Fe Average atomic mass1.The ____________________________ is a weighted Ironaverage that reflects the abundance of different 55.845isotopes. Mass number2.The ______________________________ is determinedby adding the number of protons and neutrons in anatom. Isotope3.__________________________ are atoms of the sameelement that have different numbers of neutrons. Atomic Number4.An element’s ____________________________ and thenumber of protons in the nucleus of its atoms arealways the same.
Different Elements—DifferentNumbers of Protons the number of protons The type of the number of electrons element
What are the atomic numbers of carbon, nitrogen and oxygen? Carbon = 6, Nitrogen = 7, Oxygen = 8Explain the difference between an oxygen atom and a carbon atom. Oxygen has 8 protons. Carbon has 6 protons.
What are two numbers the can be used to identifyan element? The number of protons and electronsExplain the difference between a Boron atom (B) and anOxygen atom. Boron has 5 protons and 5 electrons Oxygen has 8 protons and 8 electronsAnalyze the periodic table and tell how you think it isorganized Organized by increasing atomic #
1. Fluorine has an atomic number of 9.What can you conclude about an atom offluorine A) It has 9 protons A) It has 9 protons
2. In what part of an atom can protons befound? C) Inside the atomic nucleus C) Inside the atomic nucleus
3. Since atoms are very small, what canyou infer about atomic mass units? D) Atomic mass units and grams D) Atomic mass units and grams Measure different properties Measure different properties
4. An atom of flourine has an atomic massof 19u, Keeping in mind that its atomicnumber is 9, what can you infer about thisatom C) It has ten neutrons C) It has ten neutrons
5. If a sulfur atom has 16 protons, 16electrons, and 16 neutrons, it’s atomicmass is? B) 32 B) 32
6. If a hydrogen atom has 1 proton, 1electron, and 1 neutron it’s atomic numberis? A) 1 A) 1
7. On the periodic table, how is the atomicmass represented? A) As an average of the mass of A) As an average of the mass of different isotopes different isotopes
8. What do carbon-12 and Carbon-14have in common? A) They have the same number of A) They have the same number of protons protons
9. How is Carbon-12 different fromCarbon-14? C) They have a different number of C) They have a different number of neutrons neutrons
10.What can you conclude aboutCarbon-14 from its name? D D
Neutrons and Isotopes• Atoms of the same element can have different numbers of neutrons.• Isotopes are atoms of the same element that have different numbers of neutrons.• Most elements have several isotopes.
Why do the isotopes of carbon in the tablehave different mass numbers? They have a different number of neutrons
Ions—Gaining or Losing Electrons• An ion is an atom that is no longer neutral because it has gained or lost electrons.• An ion can be positively or negatively charged depending on whether it has lost or gained electrons.
• When a neutral atom loses one or more electrons, it has more protons than electrons and as a result, has a positive charge.• An atom with a positive charge is called a positive ion.
• When a neutral atom gains one or more electrons, it now has more electrons than protons and as a result, has a negative charge.• An atom with a negative charge is called a negative ion.
neutralAn ion is an atom that is no longer ________________ because ithas gained lost______________________ or _____________________ electrons. An atom that lost An atom that gained an electron an electron Positive Charge Negative Charge
Ions—Gaining or Losing Electrons (cont.) How does a neutral atom change when its number of protons or electrons changes?