Transcript Atomic Structure, Physical and Chemical Changes

Unit 1.3- Physical and
Chemical Properties
Structure of the Atom
• Protons: Positively charged subatomic particle
located in the nucleus
• Neutron: No charge subatomic particle located in the
nucleus
• Electron: Negatively charged particle located in the
electron cloud
• Nucleus: The positively charged center of the atom
• Orbitals: When electrons move
• Further from the nucleus= higher energy
Sub-Atomic Particles Chart
Orbital Arrangement
• Orbitals get closer and closer together, the
further they are away from the nucleus
• Orbitals increase in energy farther away from the
nucleus
• The first orbital can hold only 2 electrons, the
second 8, third 18, 4th 32, etc.
Elements from the periodic Table
• The number of protons present in an atom are what makes the atom the element it
is.
• Example:
• Every Hydrogen (H) atom contains 1 proton
• Every Carbon (C) atom contains 6 protons
• The number of electrons determines = the number of protons in an atom
• Carbon atoms have 6 protons, so they have 6 electrons
• The number of Neutrons in an atom can vary. This creates Isotopes.
• Isotopes- are atoms of the SAME element with DIFFERENT numbers of neutrons
• Carbon has 6 protons
• An atom of carbon can have 6 neutrons or 8 neutrons
Elements from the periodic Table
• Atomic Number- Number of
Protons in the nucleus
• Mass Number- Protons plus
neutrons
• Atomic Mass- Average mass of
the atoms in an element (this
takes into account the mass of all
the isotopes and makes an
average mass)
• Isotope- an atom of an element
with a different number of
neutrons
Calculating Number of Sub-Atomic Particles
Element
Name
Element
Symbol
Atomic
Number
Li
3
Atomic Mass
# Protons
K
# Electrons
6
6
Potassium
# Neutrons
40
16
7
19
8
Physical and Chemical Properties
• Physical Properties: Properties you can observe without chemically changing the
nature of the substance
• Examples: color, smell, freezing point, melting point, boiling point, density, texture
• Chemical Properties: Properties you observe while chemically changing the nature
of the substance
• pH, reactivity in water, heat of combustion, flammability
Physical and Chemical Changes
• Physical Changes: do not change what the substance is, but it can change
the state of matter (solid, liquid, or gas) and size or texture
• Example: crushing, ripping, freezing, melting, tearing
• Chemical Changes: change what the substance is through chemical means
• Examples: rusting, burning,
Evidence of a Chemical Change
1. Light (Igniting Magnesium)
2. Bubbles or creating a gas (Magnesium reacting with hydrochloric acid)
3. Heat (Magnesium with hydrochloric acid)
4. Color Change (Lead Nitrate plus Potassium Iodide)
5. Precipitate or making a solid (Lead Nitrate plus Potassium Iodide)
Types of Matter
• Element: A pure substance that cannot be broken
down into any other substances by chemical or
physical means. (Simplest Substances)
• Atom: The basic particle from which elements are
made of
• Molecules: 2 or more atoms chemically combined
• Compounds: 2 or more elements chemically
combined in a set ratio
Difference in Properties
• When elements are chemically combined, they form compounds that
have different properties from the uncombined elements.
• Example:
Name:
Symbol:
Appearance
Melting Point
Density
Sodium
Na
Silvery-white
solid
Explodes in
water
97.79
966 kgm-3
Chlorine
Cl
Yellow-green gas
Toxic
-101.5
2030 kgm-3
Sodium
Chloride (table
salt)
NaCl
colorless solid
crystals
YUM
801
2.16