Test

vocabulary

100

Element

pure substance made of one type of atom 

200

Compound

Mixture

Substance made of two or more different elements chemically combined

Physical combination of substances

300

Ionic bond

Covalent bond

electron transfer → positive & negative ions

electron sharing

400

Chemical formula

Reactants

element symbols + subscripts showing number of atoms in a molecule 

C₆H₁₂O₆

Reactants → Products — chemical equation components; + means “and”; arrow shows direction (→ one way, ⇌ reversible).

500

Chemical energy

Energy stored in chemical bonds; can transform to thermal, light, sound.

Lewis Dot

100

what is the Lewis dot diagram?

 shows valence electrons

200

Explain what neon looks like with the Lewis dot structure

     _..                                                                               :Ne:                                                                                     ^..

Got something like this? Good!

300

How do you draw the Lewis dot structure? what do the dots represent?

Write element symbol; place one dot per valence electron around symbol (up to 8).

400

what are the groups numbers?

• Group → valence electrons: Group 1 → 1, Group 2 → 2, Group 13 → 3, Group 14 → 4, Group 15 → 5, Group 16 → 6, Group 17 → 7, Group 18 → 8 (noble gases inert).

500

Why do atoms form bonds?

• Atoms form bonds to attain full valence shell (octet or duet for H).

Binding patterns

100

Chemical bond

attraction between atoms (ionic, covalent)

200

Bonding pattern for:

Ionic bonds

metal loses e− → 

cation; nonmetal gains e− → anion.

 Example: Na (1 valence) + Cl (7 valence) → Na+ Cl− → NaCl (ionic lattice).

300

Bonding pattern for:

Covalent bonds

atoms share e−. 

Example: H2O — O shares one e− with each H → O has 8 electrons overall; each H has 2 (duet).

400

Bonding pattern for:

 single bond

one pair shared (−). Double bond = two pairs shared (=). Example: O=O (oxygen double bond).

500

Lewis-dot based bonding tips

• Count total valence electrons, place atoms, form bonds to satisfy octets (H wants 2).

chemical formulas

100

First step?

1. Identify elements and their counts from name or structure.

200

Second step?

2. Metals first, then nonmetals (for ionic write cation then anion)

300

Third step?

3. Balance charges for ionic compounds

400

Forth step?

Use subscripts to show counts; no subscript = 1.

500

example:

glucose → C₆H₁₂O₆.

chemical equations

100

what side is the reactant on and hat side is the product on?

reactants (left) and products (right)

200

do we use whole numbers before formulas to balance atoms on both sides?

Yes

300

We don't check polyatomic ions;

true or false?

False, 

We check polyatomic ions that remain intact on both sides — balance them as a unit.

400

is there one more check?

yes, 

total atoms of each element equal on both sides; total mass conserved.

500

exaple:

Reactants: H2O2 → Products: H2O + O2