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What is an atom?
The smallest part of an element that retains the properties of that element.
What is an atom made of
Protons, Neutrons and Electrons
What are protons?
Positively charged particles in the nucleus.
What are neutrons?
Particles of the nucleus that have no electrical charge.
What is atomic mass unit?
A unit of mass used to express the mass of an atom or molecule .
What are electrons?
Negatively charged particles outside the nucleus.
Where do we find electrons?
Orbiting around the nucleus in energy levels, shells, or clouds.
What is an electron cloud?
A region around the nucleus of an atom where electrons are likely to be found.
Do atoms have an overall charge?
Atoms have no overall charge unless the number of electrons and protons are unequal
How do atoms have a positive or negative charge?
When the electrons and protons in the atom are not equal
What are ions?
Charged particle formed when electrons and protons are not equal.
What is the charge of an ion if we have more electrons?
More electrons means a negatively charged ion
What is the charge of an ion if we have more protons?
Less electrons means a positively charged ion
Do all atoms contain neutrons?
No. Hydrogen does not.
What is atomic number?
The # of protons in the nucleus
What are isotopes?
Are atoms that have the same number of protons but have different numbers of neutrons
List some properties of isotopes.
Some isotopes are unstable. An unstable atom is an atom with a nucleus that will change over time – radioactive. Radioactive atoms spontaneously fall apart over time.
How can we tell isotopes apart?
You can tell isotopes of an element apart by its mass number. mass number = protons + neutrons
What is the mass number?
mass number = protons + neutrons
What is atomic mass?
the mass of an atom expressed in atomic mass units; a weighted average of the masses of natural isotopes of that element.
Name the four forces in an atom.
- Gravitational force
- Electromagnetic force
- Strong force and
- Weak force
Who discovered the periodic table? What year?
Dmitri Mendeleev- 1869
How did Mendeleev arrange the elements?
He arranged them in order of increasing atomic mass.
What did Henry Mosely determine?
He determined the number of protons (the atomic number) in an atom.
What is the Periodic Law?
The Periodic Law states that the repeating chemical & physical properties of elements change periodically with the elements' atomic numbers.
Where do we find metals on the periodic table?
LEFT of the zigzag line on the table.
List some properties about metals.
- Most metals are solid at room temperature (except for Mercury).
- Ductile - drawn into thin wires
- Good conductors of electric current
- Good conductors of thermal energy
- Malleable - flattened with hammer and won't shatter.
Where do we find nonmetals on the periodic table?
Found right of the zigzag line on the table
List some properties of nonmetals.
- More than ½ are gases at room temp.
- Not malleable or ductile, not shiny, poor conductors of thermal energy and electric current
Where do we find metalloids on the periodic table?
These border the zigzag line on the table.
List some properties of metalloids.
Have some properties of both metals and some properties of nonmetals.
How do we identify an element?
Each element is identified by a chemical symbol. Symbols are worldwide.
What are horizontal rows called?
Horizontal rows (from left to right) are called PERIODS.
What changes gradually as you move from left to right?
Conductivity and reactivity change gradually as you move left to right.
What are vertical columns called?
Vertical columns (top to bottom) are called GROUPS.
Elements in the same group often have similar __________ and __________ properties.
Elements in the same group often have similar chemical and physical properties.
A group is also called a __________.
A group is also called a FAMILY
Why are the properties in groups similar?
Properties in a group are similar because the atoms have the same number of electrons in their outer energy levels.
What will atoms do in order to have a complete set of electrons?
Atoms will take, give or share electrons with each other in order to have a complete set of electrons.
Elements that obtain a complete set of electrons are said to be ____________.
Elements that undergo this process are called reactive.
Name all the groups.
G1) Alkali Metals, G2) Alkaline-Earth Metals, G3-12) Transition Metals, G13) Boron, G14) Carbon, G15) Nitrogen, G16) Oxygen, G17) Halogens, G18) Noble Gases and Hydrogen.
Identify each group as metal, metalloid, nonmetal or combination: Alkali Metals, Alkaline-Earth Metals, Transition Metals, Boron, Carbon, Nitrogen, Oxygen, Halogens, Noble Gases and Hydrogen.
- Alkali Metals, Alkaline-Earth Metals, Transition Metals: metals
- Boron, Carbon, Nitrogen, Oxygen: combination
- Halogens, Noble Gases and Hydrogen: nonmetal
Name an element in each group.
Define 1) atomic mass unit, 2) atomic number, 3) mass number and 4) atomic mass.
- 1) atomic mass unit: A unit of mass used to express the mass of an atom or molecule.
- 2) atomic number: The # of protons in the nucleus
- 3) mass number: protons + neutrons
- 4) atomic mass: a weighted average of the masses of natural isotopes of an element.
What group(s) has these properties: softness, silver color, shiny, low density
Alkali Metals Group 1
What group(s) has these properties: silver color, higher density than alkali metals
Alkaline Earth Metals Group 2
What group(s) has these properties: shiny, good conductors of thermal energy, good conductors of electric current, higher density and melting points than elements in Group 1 & 2 (except mercury), malleable.
Transition Metals Groups 3-12
What group(s) has these properties: solids at room temperature
- Boron Group 13, and
- Carbon Group 14
- Nitrogen Group 15 (except for Nitrogen: gas)
- Oxygen Group 16 (except for Oxygen: gas)
What group(s) has these properties: violently reacts with Alkali Metals to form salts; never in uncombined forms in nature; poor conductors of electric current.
Halogen Group 17
What group(s) has these properties: colorless, odorless gases at room temperature
Noble Gases Group 18
What group(s) has these properties: colorless, odorless gas at room temperature; low density; explosive reactins with oxygen.