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Transcript of Review Scientist who discovered the electron using the cathode ray tube –Thomson Scientist who...
Review
• Scientist who discovered the electron using the cathode ray tube
–Thomson• Scientist who used the oil drop experiment to
discover the charge on the electron
–Millikan• Scientist who conducted the gold foil
experiment to discover that the nucleus is small, dense, and positively charged.
–Rutherford
Review
• Scientist that developed the pulsating planetary model
–Bohr• Scientist that discovered the existence of the
neutron
–Chadwick• Scientist that had the solid sphere model of
the atom
–Dalton
Review
• Greek philosopher who coined the term atom from the Greek word atomos
–Democritus• Greek philosopher who did not believe in the
atom
–Aristotle• Scientist who created the law of definite
proportions
–Proust
Review
• Scientist who created the law of multiple proportions
–Dalton• Scientist who created the law of conservation
of mass
–Lavoisier
Review
• An An atomatom is the smallest particle of an is the smallest particle of an element that gives it its chemical and element that gives it its chemical and physical properties.physical properties.
• The atom is extremely small. One teaspoon The atom is extremely small. One teaspoon of water has 3 times as many atoms as the of water has 3 times as many atoms as the Atlantic Ocean has teaspoons of water.Atlantic Ocean has teaspoons of water.
• If a large sports stadium were an atom, a If a large sports stadium were an atom, a marble would represent the nucleus.marble would represent the nucleus.
An atom consists of aAn atom consists of a
• Positively Positively charged nucleus that contains charged nucleus that contains protonsprotons and and neutronsneutrons
• Negatively Negatively chargedcharged electrons electrons in space outside in space outside of the nucleus.of the nucleus.
Atom Atom StructureStructure
NucleusNucleus
Electron cloudElectron cloud
Atoms found in nature have a neutral charge.
Why?
Atomic NumberAtomic Number
All atoms of the same element All atoms of the same element have the same number of have the same number of protons in the nucleusprotons in the nucleus
1313
AlAl
26.98126.981
Atomic numberAtomic number
Atom symbolAtom symbol
AVERAGE Atomic MassAVERAGE Atomic Mass
Atomic NumberAtomic Number
Atomic # = # protons =
# electrons
*only for neutral atoms
Mass NumberMass Number
• Mass NumberMass Number
= # protons + # neutrons= # protons + # neutrons
• NOT on the periodic table, NOT on the periodic table, electron is so small that its mass is electron is so small that its mass is negligiblenegligible
Average Atomic Mass
•Weighted average, more abundant isotopes have a greater affect
–On the periodic table
Atomic Symbols
Hyphen/mass notation - show the name of the
element, a hyphen, and the mass number in
sodium-23
Nuclear symbol - show the mass number and atomic
number next to the chemical symbol
mass number 23 Na
atomic number 11
Figure 3.10: Two isotopes of sodium.
IsotopesIsotopes
• Atoms of the Atoms of the same element same element but but different different mass numbermass number..
• Boron-10 (Boron-10 (1010B) has 5 p and 5 nB) has 5 p and 5 n
• Boron-11 (Boron-11 (1111B) has 5 p and 6 nB) has 5 p and 6 n
10B
11B
Practice
•Ar-40
•P-31
Isotopes?
Which of the following represent isotopes of the same element? Which element?
234 X 234
X235
X238
X
92 93 92 92
1.1. An An __ _____ ___ is the smallest particle of is the smallest particle of an element that has the chemical properties an element that has the chemical properties of the element.of the element.
2. The 3 particles that make up the atom 2. The 3 particles that make up the atom are are ________________, , __________________, and , and __________________..
3. Atoms with the same number of protons 3. Atoms with the same number of protons and electrons, but a different number of and electrons, but a different number of neutrons are called neutrons are called ________________________..
4. 4. ______________________ was an English scientist was an English scientist who developed an atomic theory in the who developed an atomic theory in the early 1800s. early 1800s.