Chapter 3: Elements and compounds

Question 1

How does the periodic table list the elements of the universe?

Answer 1

By order of increasing proton number

Question 2

Some properties of metallic elements:

Answer 2

• usually solid with high melting and boiling points
• hard and dense
• all good conductors of heat and electricity
• malleable(change shape easily) and ductile(pulled into wires)
• make a ringing sound when struck

Question 3

Some properties of non-metal elements:

Answer 3

• solids or gases at room temp and have low melting and boiling points
• softer than metals with low densities
• poor conductors of electricity (insulators)
• poor thermal conductors
• brittle when solid
• don’t make a sound when struck

Question 4

How is group one- alkaline metals grouped vertically?

Answer 4

• increasing down in reactivity
• decreasing down in melting and boiling point
• increasing down in density

Question 5

How is group 7 -halogen - the periodic table grouped vertically?

Answer 5

• decreasing down in reactivity

- increasing down with melting and boiling point

Question 6

What are some common properties of halogens?

Answer 6

• react with oxygen to form halogen oxides
• react with metals to form metal halides (salts)
• form negative ions
• form compound with oxygen that are strong acids which dissolve in water
• used as oxidizing agents

Question 7

Why are alkaline metals known as alkaline metals?

Answer 7

because they react vigorously with water to produce hydrogen and an alkaline solution.

Question 8

How is group 8-the noble gases- in the periodic table grouped vertically?

Answer 8

• increasing in reactivity down the group

- increasing down the group in the melting and boiling point

Question 9

How are trends across a period grouped?

Answer 9

elements in the same period of the periodic table have the same number of energy levels just different electron in the outer shell dependent on the group

Question 10

What are the trends in reactivity in periods?

Answer 10

• for metal elements reactivity decreases from left to right

- for non-metal elements reactivity decreases from right to left

Question 11

Define ion:

Answer 11

any particle that has a charge by gaining or loosing electrons.

Question 12

How are metallic elements bonded?

Answer 12

With a metallic bond that results in metallic lattices

Question 13

How are non-metal elements held together?

Answer 13

by covalent bonding that results in simple molecules or giant molecular lattices.

Question 14

What are some features of covalent bonding?

Answer 14

• bond is formed by the sharing of a pair of electrons between two atoms
• each atom contributes one electron to each bond
• molecules are then formed by the atoms linked together

Question 15

What is ionic bonding?

Answer 15

• metal + non-metal
• involves the transfer of electrons from one atom to another
• this causes the formation of positive and negative ions
• the oppositely charged ions are attracted to each other by electrostatic forces

Question 16

Properties of ionic compounds:

Answer 16

• crystalline solids at room temperature
• have high melting and boiling points
• often soluble in water
• they conduct electricity when molten or dissolved in water

Question 17

Properties of covalent compounds:

Answer 17

• often liquid and gases at room temperature
• low melting and boiling points
• soluble in organic solvents like ethanol or methylbenzene
• don’t conduct electricity

Question 18

What are alloys?

Answer 18

a mixture of two or more elements with a certain fixed composition in which the major component is metal.

Question 19

How does an alloy work?

Answer 19

because two metals are put together there are different size atoms in the metals and so those layers can’t slide off so easily like pure metals making them much stronger