UNIT 2 - The Periodic Table & Chemical Properties Flashcards
Lesson 01/28/2025
Who introduced the first methods for organizing elements in the Periodic Table?
Dmitri Mendeleev
How did Mendeleev arrange the elements?
By increasing atomic mass and grouped by similar properties.
What assumption did Mendeleev make about the elements?
Some elements were still undiscovered, leaving areas of the table blank.
How is the modern periodic table ordered?
By increasing atomic number.
What information does each box in the periodic table provide?
Element’s name, symbol, atomic number, atomic mass, and common ion charge(s).
What is the atomic number?
The number of protons in an atom’s nucleus, identifying the element.
What pattern does the atomic number follow across rows?
It increases by one.
What is atomic mass?
The average mass of all atoms of one element, measured in atomic mass units (amu).
What pattern does atomic mass follow?
It tends to increase along with the atomic number.
What does ion charge represent?
The electric charge of the ion, indicating if an atom gains or loses electrons.
What does a negative ion charge indicate?
The atom has gained electrons.
What does a positive ion charge indicate?
The atom has lost electrons.
What is the pattern for ion charges among elements?
Metals (left) tend to have positive ions; nonmetals (right) tend to have negative ions.
What defines a chemical family in the periodic table?
Elements in the same group have similar chemical and physical properties.
What are the two arrangements in the modern periodic table?
Groups (vertical) and periods (horizontal).
How many periods are in the modern periodic table?
There are 7 periods.
What are main group elements?
Elements in Groups 1, 2, and 13 to 18.
What are transition elements?
Elements in Groups 3 to 12.
What are alkali metals?
Group 1 elements, highly reactive, including Li, Na, K, Rb, Fr (NOT H).
What are the characteristics of alkali metals?
Highly reactive, low melting point, very soft.
What are alkaline earth metals?
Group 2 elements, including Be, Mg, Ca, Sr, Ba, Ra.
How do alkaline earth metals react?
Less reactive than Group 1, burns in air if heated, reacts with water.
What are halogens?
Group 17 elements, highly reactive nonmetals including F, Cl, Br, I, At.
What are noble gases?
Group 18 elements, most stable and unreactive nonmetals including He, Ne, Ar, Kr, Xe, Rn.
