Development of the Atomic Theory pg 82 – 88
Name:__Key_________
Atom – smallest particle into which an element can be divided and still be the same
substance.
Dalton’s Atomic Theory
- All substances are made of atoms. Atoms are small particles that cannot be
created, divided or destroyed. (later we proved they can be created, divided and
destroyed.)
- Atoms of the same element are exactly alike, and atoms of different elements are
different.
- Atoms join with other atoms to make new substances.
** this is still changing as we discover new things. **
The Atom pg 88 – 91
How small is an atom? 0.00000003 cm
Atoms are made up of particles called, protons, neutrons, and
electrons
Nucleus – tiny dense, positively charged center of an atom
Protons -are positively charged particles in the nucleus
- they have the mass of 1.7 x 10-24 g or 1 atomic mass unit (amu)
Neutrons – particles in the nucleus with no charge.
- mass of 1 amu
Electron clouds- regions around the nucleus where electrons are likely to be found.
Electrons
- negatively charged particle in atoms, found around the nucleus in the
electron clouds.
- Very small, it takes more than 1,800 electrons to equal the mass of a proton.
- Charge of an electron is opposite of a proton. Therefore 1 proton & 1
electron cancel one another.
Atomic Number
- tells the number of protons in the nucleus
- all atoms of an element have the same atomic number.
Atomic Mass (pg. 93)
- mass of an atom expressed in atomic mass units (see above)
- tells you the number of protons and neutrons in nucleus of the atom
How to read a Periodic table of elements
Atomic number
amount of protons
79
Name
Au
Gold
197.0
Symbol
Atomic mass
- average mass of atom
- tells how many protons and
neutrons
Development of the Atomic Theory pg 82 – 88
Name:________________________
Atom –
Dalton’s Atomic Theory
- ______________________________________________________________________________________.
Atoms are small particles that cannot be created, divided or destroyed. (later we
proved they can be created, divided and destroyed.)
- ______________________________________________________________________________________, and
atoms of different elements are different.
- ____________________________________________________________________________________________.
** this is still changing as we discover new things. **
The Atom pg 88 – 91
How small is an atom? _______________________________ cm
Atoms are made up of particles called, _______________________,
__________________________, and __________________________.
Nucleus – ____________________________________________ of an atom
Protons -are ___________________________________________in the nucleus
- they have the mass of 1.7 x 10-24 g or 1 atomic mass unit (________)
Neutrons – _____________________ in the nucleus with ____________________________.
- mass of 1 amu
__________________- regions around the nucleus where electrons are likely to be found.
Electrons
- ______________________________________________ in atoms, found around the nucleus
in the electron clouds.
Electrons continued
- ______________________, it takes more than 1,800 electrons to equal the mass of a
proton.
- ________________________________ of an electron is opposite of a proton. Therefore
______________________ & _______________________ cancel one another.
Atomic Number
- tells the number of __________________________ in the nucleus
number of protons in an atom tell you which ____________________ it is.
- all atoms of an element have the same atomic number.
Atomic Mass (pg. 93)
- mass of an atom expressed in atomic mass units.
- tells you the number of _________________________ and _______________________ in the
nucleus of the atom.
How to the elemental squares on a periodic table. (page 108)
79
Au
Gold
197.0