the atom: structure. inside the atom electrons protons neutrons nucleus beryllium atom

Download The Atom: Structure. Inside the Atom Electrons Protons Neutrons Nucleus Beryllium Atom

Post on 21-Jan-2016




2 download

Embed Size (px)


  • The Atom:Structure

  • Inside the AtomElectronsProtonsNeutronsNucleusBeryllium Atom

  • Nucleus-small, dense, overall positive charge

    -located at center of atom

    -contains most of atom's mass

    -contains protons & neutrons

    -very dense

  • Protons-same size and mass

    - used to set the unit for mass of subatomic particles

    -called the atomic mass unit (amu) ; 1 proton = 1 amu

    -charge: positive

    -mass: 1 amu

    -location: nucleus

  • Neutrons-all identical

    -slightly larger than protons (not enough to matter)

    -charge: none (neutral)

    -mass: 1 amu

    -location: nucleus

  • Electrons-smaller than protons

    -equal and opposite in charge

    -size of electron clouds determinesthe size of the atom

    -charge: negative

    -mass: zero

    -location: electron clouds outside the nucleuselectron-

  • Ions-atoms are neutral (no overall charge)-due to equal but opposite charge of protons & electrons-protons & electrons are equal in number, so their charges cancel out-if number of protons & electrons becomes unequal, atom becomes and ion-number of protons > number of electrons = positive charge-number of protons < number of electrons= negative charge

  • Differences in Atoms-each element has a different number of protons, neutrons, & electrons-the more it has, the larger it isEX:-Hydrogen: 1 proton, 1electron, 0 neutrons-Helium: 2 protons, 2 neutrons (help hold the nucleus together), 2 electrons

  • Telling them Apart-the number of protons in an atom is its atomic number

    -determines what element an atom represents

    -all atoms of an element have the same atomic number

    EXAMPLE:Oxygen has 8 protons, so its atomic number is 8.Atomic Number

  • Same Element, Different Atom-isotope atoms (of the same element) with the samenumber of protons, but a different number of neutrons

    -EX:A) add a neutron to a hydrogen atomB) mass now different, but atomic number still 1C) still hydrogen, but different isotope

  • Properties of Isotopes-each element has a limited number of naturallyoccurring isotopes-isotopes of an element share most physical & chemical properties-some isotopes unstable & therefore radioactive-isotopes of an element identified by mass number -mass number = protons + neutrons-named by writing: element name-mass number

    EXAMPLE: Hydrogen with a mass number of 2: Hydrogen-2

    Boron with a mass number 10: Boron-10

  • Mass of Elements-most elements contain two or more isotopes

    EX: All Copper (Cu) is made of Copper-63 and Copper-65 atoms

    -atomic mass is a weighted average of each isotope present (a weighted average goes by the percent of each isotope)

    EX: Copper is 69% copper-63 & 31% copper-65

  • Forces in the Atom-4 basic forces at work in the atom:

    1) Gravity - force of attraction that pulls objects toward each other. Depends on mass of the objects anddistance between them. Force of gravity in the atom is very small.2) Electromagnetic Force - causes like charges to repel and opposite charges to attract. Holds electrons in place around the nucleus.3) Strong Force - helps hold the nucleus together At close distances is stronger than the electromagnetic force.4) Weak Force helps convert neutrons into protons or electrons in unstable (radioactive) atoms.

  • **************


View more >