Chemical Equations

Element or Compound?

Groups:

(a) Element

,

(b) Compound

• Fe

• CO₂

• O₂

• Zn

• H₂O

• CBr₄

• H₂

• SiO₂

Tags

NGSS.MS-PS1-1

The elements in a formula are identified by their ​ (a)   .

• symbols
• numbers
• subscripts

Tags

NGSS.MS-PS1-1

Lowercase letters are ​ (a)   part of a 2-letter symbol.

• sometimes
• never
• always

Tags

NGSS.HS-PS1-1

Chemical formulas describe the number of ​ (a)   of each element in the substance.

• electrons
• protons
• atoms

Tags

NGSS.MS-PS1-1

2Al + 6HCl₂ ---> AlCl₃ + 3H₂

How many different elements are taking part in the chemical reaction shown above?

2Al + 6HCl₂ ---> AlCl₃ + 3H₂

How many atoms are represented in the reactants of the chemical equation that has been written above?

• 3

• 10

• 30

• 20

Tags

NGSS.MS-PS1-1

2Al + 6HCl₂ ---> AlCl₃ + 3H₂

The products shown in the chemical reaction above would best be classified as –

• Two elements

• An element and a compound

• Two compounds

• A compound and a mixture

Tags

NGSS.MS-PS1-1

2Al + 6HCl₂ ---> AlCl₃ + 3H₂

The reactants shown in the chemical reaction above would best be classified as –

• Two elements

• An element and a compound

• Two compounds

• A compound and a mixture

Element or Compound?

Groups:

(a) Element

,

(b) Compound

• Na

• He

• Fe₂O₃

• Al₂S₃

• Cl

• NaCl

• SF₆

• Zn

Tags

NGSS.MS-PS1-1

In a chemical formula, the large number in front is called the ​ (a)   , and the small numbers at the bottom are called ​ (b)   .

• coefficient
• subscripts
• atomic numbers