unit 2.1-2.2

What were the four classical elements proposed by Empedocles?

Earth, air, fire, and water

What was Aristotle's fifth element?

Ether

What is an element?

A substance that cannot be broken down into simpler substances by ordinary chemical means

What is the Law of Conservation of Mass?

The total mass of the reactants equals the total mass of the products; mass is not created or destroyed

What is the Law of Definite Proportions?

A specific compound always contains the same elements in the same fixed proportions

What is the Law of Multiple Proportions?

The same elements can combine in different ratios to form different compounds, such as CO and CO2

Which ancient element symbols should I recognize?

Fe, Pb, Hg, Ag, Sn

Who created an early periodic table in 1869?

Dmitri Mendeleev

How did Mendeleev arrange his periodic table?

By increasing atomic mass while grouping elements with similar properties

Why did Mendeleev leave gaps in his periodic table?

He predicted that undiscovered elements would eventually fill them and predicted their properties

How is the modern periodic table arranged?

By increasing atomic number

What is the Periodic Law / periodicity?

When elements are arranged by increasing atomic number, their properties repeat in predictable patterns

What is a period?

A horizontal row on the periodic table

What is a group or family?

A vertical column; elements in the same group have similar properties

Where are metals, nonmetals, and metalloids located?

Metals are mainly left/centre, nonmetals are mainly right, and metalloids are along the staircase

What are Groups 1, 2, 17, and 18 called?

Group 1 Alkali Metals; Group 2 Alkaline Earth Metals; Group 17 Halogens; Group 18 Noble Gases

What groups are the transition elements?

Groups 3-12; they are all metals

What is the general main-group combining-capacity pattern?

+1, +2, +3, +4, -3, -2, -1, 0

What is unusual about hydrogen's position?

Hydrogen can show properties similar to both Group 1 and Group 17

What diatomic elements should I memorize?

HOBrFINCl = H2, O2, Br2, F2, I2, N2, Cl2

What multiatomic elemental forms should I remember?

Phosphorus is P4 and sulfur is S8

What is atomic radius and what is its trend?

Atomic radius is atom size; it decreases moving right and increases moving down

What is ionization energy and what is its trend?

Energy required to remove the outermost electron; it increases moving right and decreases moving down

What equation represents ionization energy?

M + energy → M+ + e-

What does M represent in an ionization-energy equation?

A generic neutral atom

What is electronegativity and what is its trend?

How strongly an atom attracts bonding electrons; it increases moving right and decreases moving down

What is electron shielding?

Inner electrons reduce the nucleus's attraction for the outer electrons

How does gaining or losing electrons affect ion size?

Gaining electrons makes a negative ion larger; losing electrons makes a positive ion smaller

Why is F- larger than F?

The extra electron increases electron-electron repulsion, making the electron cloud larger

How do you find valence electrons from a simple electron configuration?

Look at the last number; for example, 2-8-7 has 7 valence electrons

How do valence electrons identify main-group groups?

1→Group 1, 2→Group 2, 3→Group 13, 4→14, 5→15, 6→16, 7→17, 8→18

What do metals and nonmetals generally do when forming ions?

Metals lose electrons and form positive ions; nonmetals gain electrons and form negative ions

What are the key Group 1 and Group 2 facts?

Group 1 forms +1 ions and gets more reactive down; Group 2 forms +2 ions, is less reactive than Group 1, and gets more reactive down

What are the key Group 17 and Group 18 facts?

Group 17 forms -1 ions and gets less reactive down; Group 18 has full outer shells and is very unreactive

What should I know about transition metals, lanthanides, and actinides?

Transition metals can have multiple charges and form coloured compounds; lanthanides are 57-71 and usually +3; actinides are 89-103 and radioactive

What is the trend for metallic character

How strongly an element shows metal properties; increases going LEFT and DOWN on the periodic table.