Question

tap water: homogeneous mixture
madison wi, water quality report 2024
water, h₂o, is a compound because it is made of the elements hydrogen and oxygen. it has 2 hydrogen atoms and 1 oxygen atom chemically combined. elements and compounds are pure substances. tap water, however, is a mixture because water flows through many different earth materials like rocks and soils and picks up such materials it dissolves other substances along the way. cities, like madison, test water that comes out of the tap for spectroscopy methods that use light energy. the city also provides a water quality report to people. the city of madison has reported its drinking water to be safe.
instructions: identify some of the substances from the madison, wi 2024 annual water quality report as elements or compounds in the table below.
*some symbols have a negative sign on top, sometimes along with a number. there is an additional classification for those substances. for now, we will just classify them as either elements or compounds.
part 1. is it an element or a compound?

1. use the examples to help you determine if the substance is an element or a compound.
2. look at the capital letters. each capital letter is a different element.

elements and compounds are pure substances

substance	symbol or formula	element or compound?
iron	fe
manganese	mn
sodium	na
sulfate	so₄²⁻	compound
arsenate	aso₄³⁻
atrazine	c₈h₁₄cln₅
barium	ba
chromium	cr
cis - 1,2 - dichloroethylene	c₂h₂cl₂

Explanation:

Step1: Recall element - compound definition

An element is a pure substance made of only one type of atom, represented by a single - capital letter symbol (or two - letter symbol where the second letter is lowercase). A compound is made of two or more different types of atoms chemically combined, represented by a formula with multiple elements.

Step2: Analyze Iron

Iron has the symbol Fe. It is made of only iron atoms, so it is an element.

Step3: Analyze Manganese

Manganese has the symbol Mn. It is made of only manganese atoms, so it is an element.

Step4: Analyze Sodium

Sodium has the symbol Na. It is made of only sodium atoms, so it is an element.

Step5: Analyze Arsenate

Arsenate has the formula $AsO_{4}^{3 - }$. It is made of arsenic (As) and oxygen (O) atoms chemically combined, so it is a compound.

Step6: Analyze Atrazine

Atrazine has the formula $C_{8}H_{14}ClN_{5}$. It is made of carbon (C), hydrogen (H), chlorine (Cl), and nitrogen (N) atoms chemically combined, so it is a compound.

Step7: Analyze Barium

Barium has the symbol Ba. It is made of only barium atoms, so it is an element.

Step8: Analyze Chromium

Chromium has the symbol Cr. It is made of only chromium atoms, so it is an element.

Step9: Analyze cis - 1,2 - dichloroethylene

cis - 1,2 - dichloroethylene has the formula $C_{2}H_{2}Cl_{2}$. It is made of carbon (C), hydrogen (H), and chlorine (Cl) atoms chemically combined, so it is a compound.

Answer:

Substance	Symbol or Formula	Element or compound?
Manganese	Mn	Element
Sodium	Na	Element
Arsenate	$AsO_{4}^{3 - }$	Compound
Atrazine	$C_{8}H_{14}ClN_{5}$	Compound
Barium	Ba	Element
Chromium	Cr	Element
cis - 1,2 - dichloroethylene	$C_{2}H_{2}Cl_{2}$	Compound