Structure of the Atom The Atom ATOM the

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Structure of the Atom

Structure of the Atom

The Atom ATOM: the smallest particle of an element that retains the identity of

The Atom ATOM: the smallest particle of an element that retains the identity of the element in a chemical reaction Just how big is an atom? Copper is an example of an element; if you were to grind a pure copper penny down to its individual atoms you would have approximately 2. 4 x 1022 atoms. The earth has only about 6. 9 x 109 people. There about 100 million Cu atoms in 1 cm 5 nm gold nanoparticles

Structure of the Atoms are divisible (can be broken down) They are made up

Structure of the Atoms are divisible (can be broken down) They are made up of 3 primary subatomic particles: Protons Neutrons Electrons All atoms consist of 2 regions: Nucleus Electron Cloud

Structure of the Atom Protons, p+ Located in nucleus Positive charge, mass of 1

Structure of the Atom Protons, p+ Located in nucleus Positive charge, mass of 1 Neutrons, no Located in nucleus No charge, mass of 1 Electrons, e. Located in the electron cloud Negative charge, mass of 0

Electrical Charges Remember that UNLIKE electrical charges ATTRACT each other, and LIKE electrical charges

Electrical Charges Remember that UNLIKE electrical charges ATTRACT each other, and LIKE electrical charges REPEL. The positive nucleus ATTRACTS the negatively charged electrons The charge on the electron balances the charge on the proton. What does this mean for our atom? An atom will contain equal # p+ and e. Atoms are electrically neutral (charge of zero)

Periodic Faceplate Name of Element Atomic Symbol Hydrogen 1 H 1. 008 Atomic Number

Periodic Faceplate Name of Element Atomic Symbol Hydrogen 1 H 1. 008 Atomic Number Atomic Mass (Weight) We characterize a nucleus by its Atomic Number (Z) and its Mass Number (A).

Atomic Number ATOMIC NUMBER (Z): indicates number of protons in the nucleus of the

Atomic Number ATOMIC NUMBER (Z): indicates number of protons in the nucleus of the atom Atomic number identifies an element. Atoms of the same elements have the same number of protons. Atoms of different elements have different numbers of protons.

Atomic Number Element Carbon (C) Atomic # (Z) 6 # of protons 6 Phosphorus

Atomic Number Element Carbon (C) Atomic # (Z) 6 # of protons 6 Phosphorus (P) 15 15 Gold (Au) 79 79

Mass Number MASS NUMBER (A): total number of nucleons in an atom (total #

Mass Number MASS NUMBER (A): total number of nucleons in an atom (total # p+ and n 0) Mass # = p+ + n 0 Since electrons have practically no mass and are located outside the nucleus, the entire mass of an atom can be considered to be located in the nucleus.

Mass Number Element Mass # (A) 12 # of protons 6 # of neutrons

Mass Number Element Mass # (A) 12 # of protons 6 # of neutrons 6 Phosphorus-35 35 15 20 Gold-197 79 118 Carbon-12

Isotopes ISOTOPE- atom of the same element having different mass due to different number

Isotopes ISOTOPE- atom of the same element having different mass due to different number of neutrons Isotopes of a particular element the same number of protons but numbers of neutrons. ALL have different Isotopes are chemically the same.

Isotopes Isotope Hydrogen– 1 (protium) p+ n 0 e- 1 0 1 Hydrogen-2 (deuterium)

Isotopes Isotope Hydrogen– 1 (protium) p+ n 0 e- 1 0 1 Hydrogen-2 (deuterium) 1 1 1 Hydrogen-3 (tritium) 1 2 1 Nucleus

Naming Isotopes of hydrogen are unusual in that they have distinct names. Identifying an

Naming Isotopes of hydrogen are unusual in that they have distinct names. Identifying an isotope requires knowing both the name or atomic number of the element and the mass of the isotope. Isotopes are usually identified by specifying their mass number.

Naming Isotopes hyphen notation : mass number is written after the name of the

Naming Isotopes hyphen notation : mass number is written after the name of the element e. g. uranium-235 U-235 nuclear symbol : shows the composition of a nucleus Mass Number Atomic Symbol Atomic Number

Determining the Number of p+ no e# p+ = Atomic Number # n 0

Determining the Number of p+ no e# p+ = Atomic Number # n 0 = Mass # - Atomic # # e- = # p+ (if neutral atom) What about if the atom is not neutral? ? ? We form an ION: atom or group of atoms with an overall positive or negative charge

Ions A N(egative) ION Anion (negative ion) = # e- increases … gains e-

Ions A N(egative) ION Anion (negative ion) = # e- increases … gains e-

Ions I’ve lost my CAT ION. Are you sure? Yes, I’m positive. Cation (positive

Ions I’ve lost my CAT ION. Are you sure? Yes, I’m positive. Cation (positive ion) = # e- decreases … loses e-

Summary of Atomic Structure PARTICLE Proton LOCATION CHARGE REL. MASS Nucleus +1 1 SYMBOL

Summary of Atomic Structure PARTICLE Proton LOCATION CHARGE REL. MASS Nucleus +1 1 SYMBOL p + Neutron Nucleus 0 1 n 0 Electron Outside the nucleus (in ecloud) -1 0 e- CHANGE? New atom Mass (Isotope) Charge (ion)

PRACTICE: Determining the Number of p+ no e. Nuclide Atomic # Mass # p+

PRACTICE: Determining the Number of p+ no e. Nuclide Atomic # Mass # p+ n 0 e- Oxygen - 18 8 10 8 Arsenic - 75 33 42 33 Phosphorus - 31 15 16 15 Nuclear Symbol