Elements, Compunds and Mixtures
What element is represented by Ca?
Calcium
What is the smallest component of an element, the basic unit of life?
atom
Compound or element
HCl
Compound
How many atoms does O₃ have?
3
Which of these compounds contains the same number of oxygen atoms?
Choose TWO correct answers.
a. Cu₃H₄O₃ c. H₃CaO
b. O₃H₅ d. CHO
C and D
How are the elements represented? How are they written?
Chemical symbols
What is a pure substance? An element, a compound, or both?
How many oxygens are there?
C₃H₄O₇
7
How many elements does
NaCl have?
2
Molecule, yes or no?
H₂
yes
How are compounds represented? What are they written with?
Chemical formulas
What is a substance made of two or more different elements?
Compound
Which of these substances are considered molecules?
O₂
CO₂
Cu
Ne
O₂
CO₂
Co(NO₂)₄ tell me how many atoms there are of each element.
Co-1
N-4
O-8
CH₂OCHFeH₂
How many hydrogen atoms does the formula above have?
5
Which are elements?
a. NaOH b. O2
c. Ca d. CHO
A and D
What is a substance made of two or more atoms?
molecule
Subscripts in a chemical formula represent:
the ratio of the number of atoms of each element present in the chemical formula
Which of the compounds contain the same number of oxygen atoms?
1. H₂SO₄ 3. Ca(ClO₂)₂
2. Fe₂O₃ 4. Mg(NO)₂
1 and 3
C₂HCaOHC₂₂
Count the number of carbon atoms in the formula above.
24
What characteristics describe an element?
1. Elements are pure substances.
2. Elements are written with lowercase letters.
3. Elements make up matter on Earth.
4. Elements are fund on the Periodic Table.
1, 3 and 4.
How many elements are in the compound NaClO₂?
3
A chemical formula is provided.
Ca3P2
What elements make up this compound?
Calcium and phosphorus
How many hydrogens does the chemical formula have?
C₃H₅N₁₀OH₃
What are two squares and a circle stuck together be considered?
a compound