23 periodic table of elements list - Free to Edit, Download ... - Free Printable

Here’s the completed “Periodic Table – Fill In” worksheet with explanations for each blank:

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Dmitri Mendeleev developed a chart-like arrangement of the elements called the Periodic Table.
→ *Mendeleev is credited with creating the first widely accepted periodic table in 1869.*

He arranged the elements in order of increasing Atomic mass, but what he discovered were many gaps.
→ *Mendeleev ordered elements by atomic mass (not atomic number, which wasn’t known then) and left gaps for undiscovered elements.*

The chart was that organized and easy to use. The arrangement used today differs from that of Mendeleev in that Henry Moseley arranged the elements in order of increasing Atomic number. He called this the Periodic law.
→ *In 1913, Moseley showed that ordering by atomic number (number of protons) made the periodic table more accurate and explained periodic trends better. This became known as the Periodic Law: “The properties of elements are periodic functions of their atomic numbers.”*

Each horizontal row of elements is called a(n) Period. Each vertical column is called a(n) Group or because of the resemblance between elements in the same column, a(n) Family.
→ *Rows = periods; columns = groups or families (since elements in the same group have similar chemical properties).*

In rows 4 through 7, there is a wide central section containing elements, each of which is called a(n) Transition metal.
→ *These are the d-block elements, located between Groups 2 and 13, known for forming colored compounds and having variable oxidation states.*

Rows 6 and 7 also contain two other sets of elements that are listed below the main chart. These are called the Lanthanide series and the Actinide series respectively.
→ *The lanthanides (elements 58–71) and actinides (elements 90–103) are f-block elements, often placed below the main table to save space.*

In Group 13 through boron and aluminum, there is a “staircase.” All elements to the left of that staircase are Metals, and all elements to the right of that staircase are Nonmetals. All of the elements touching the staircase (except Al) have some but not all of the properties of metals, and are called Metalloids.
→ *The staircase separates metals (left) from nonmetals (right). Elements along the staircase — B, Si, Ge, As, Sb, Te, Po — are metalloids (semimetals), exhibiting mixed properties.*

Each of the elements in Group 1 is called a(n) Alkali metal.
→ *Group 1 (excluding H): Li, Na, K, Rb, Cs, Fr — highly reactive metals that form +1 ions.*

Each of the elements in Group 2 is called a(n) Alkaline earth metal.
→ *Group 2: Be, Mg, Ca, Sr, Ba, Ra — reactive metals that form +2 ions.*

Each of the elements in Group 17 is called a(n) Halogens.
→ *Group 17: F, Cl, Br, I, At, Ts — highly reactive nonmetals that form -1 ions.*

Each of the elements in Group 18 is called a(n) Noble gas.
→ *Group 18: He, Ne, Ar, Kr, Xe, Rn, Og — inert gases with full valence shells, very low reactivity.*

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✔ Final Answer (Blanks filled in order):

1. Periodic Table
2. Atomic mass
3. Atomic number
4. Periodic law
5. Period
6. Group
7. Family
8. Transition metal
9. Lanthanide series
10. Actinide series
11. Metals
12. Nonmetals
13. Metalloids
14. Alkali metal
15. Alkaline earth metal
16. Halogens
17. Noble gas

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