Mathematical Equations
Use numerals for numbers in mathematical contexts (e.g., when the number is used in calculations), including word problems.
Accessibility: MathML/LaTeX should be used whenever possible to generate equations that a screen reader can handle. When this is not possible, be sure to adhere to the practice of using spaces between terms in an equation (See "Spacing Equations").
Angles: Use the symbol ∠ when used with a number and the word angle without a number.
Example:
∠1 = 55° but "What is the measure of the angle . . . ?"
Exception:
As with numerals, spell out when used at the beginning of a sentence.
Dates: Dates should not be used in problems requiring calculation. Instead, present time periods as days or weeks.
Fractions: Simple fractions in text should be expressed as 3/4, 5/9. However, the automated fractions in Word may also be used. Additionally, fractions in display and in cases where there are multiple fractions or equations should use the horizontal bar with the numerator and denominator clearly delineated. Use the horizontal bar fractions in objective assessments.
Hyphenation: Hyphens are never used between the numeral and the abbreviation or symbol, even when they are in adjectival form (e.g., 12 ft building).
Minus/negative signs: Use en dashes (ALT+0150) for minus/negative signs (e.g., x – n). Do not put a space between a number and its negative sign (e.g., –4 not – 4).
Multiplication signs: Use the specified Word symbol × (ALT+0215), not a roman x for the multiplication symbol. When referring to a matrix or table, the multiplication symbol should also be used (e.g., a 2 × 2 matrix). In some mathematical contexts, an asterisk may be appropriate to indicate multiplication.
Naming figures: Refer to figures starting with top left (e.g., ABCD).
Parentheses: Parentheses next to variables should not be italicized because the parentheses are seen as part of the equation as a whole
Example:
f(x) = 5x + 1/(x + 7)
Parenthetical multiplication: It is also acceptable to use parentheses to indicate multiplication. When a number and a variable are multiplied, place the number first and do not use any multiplication symbol. The character • should be avoided.
Examples:
4 × 12
(x – y)(12 + x)
3x
Pi: The term pi should be replaced with the pi symbol (π).
Points: Points should be capitalized (e.g., the coordinates for Point A are (4, 2)).
Solution: Use "No real number solution"; not "No real solution" or "No solution."
Space between coordinates: One space should be used between the numbers representing coordinates on a graph. A nonbreaking space is recommended when possible. Example: (4, 2) not (4,2).
Spacing equations: Use a nonbreaking space between all terms in equations (e.g., 4x – 2 = y). Using nonbreaking spaces will prevent most equations from being split in two by soft line breaks.
Exceptions:
Spacing with parenthetical multiplication: Leave no space between a number and parentheses when using parentheses to denote multiplication. Example: 2(3 – 4) rather than 2 (3 – 4).
Spacing with slashes: When slashes are used to indicate division or a fraction in equations, do not use a space before and after the slash. Example: 4/8x rather than 4 / 8x.
Squared/cubed units: Express squared and cubed units by using the abbreviated unit with an exponent when a numeral precedes it.
Example:
Use 12 ft² instead of 12 square feet.
Statistical terminology: Statistical terms (e.g., t test, p value) should align with APA 7 usage and formatting. (See APA 7, Section 6.13 and "Statistical and Mathematical Copy.")
Variables: Variables (e.g., x, y, i ) should be italicized. Names of angles and triangles (ΔABC, ∠A) should also be italicized, as they are variables. This includes variables when referring to an axis (e.g., x-axis) and the variable that signals a function f(x).
Exception:
Greek letters that are not being used as variables (e.g., Δ, Σ) should not be italicized. Those that are being used as variables (e.g., α, β) should be italicized. Numbers that are next to a variable, including those in superscript or subscript, should not be italicized.
Zeros with decimals: Use zeros before decimal fractions with no whole number.
Example:
0.18
Exception:
Do not place a 0 before the decimal when referring to a probability.
Chemistry Formatting
Summary
The American Chemistry Society Style Guide (referred to as ACS for short) was consulted to create these entries that specifically relate to stylizing chemistry. Please note that some formula examples were pulled from the ACS style guide. For more information on editing chemistry material, use the ACS link above. If possible, you may wish to consult a SME on any chemistry-related projects if you are uncertain how to interpret a number, letter, word, or symbol.
Spacing
Equations, reactions, formulas, compounds, etc.: WGU's rule of adding nonbreaking spaces between all terms applies to chemistry equations. This includes inserting spaces before and after operators and arrows in chemical reactions.
Example:
2Al + 6NaOH → 2Na3AlO3 + 3H2.
However, spaces of any kind should not be applied to the following:
- between coefficients and elements (ACS, p. 272)
- "in any part of a superscript or subscript, unless confusion or misreading would result" (ACS, p. 219)
- "between any character and its own superscript, prime, or subscript" (ACS, p. 219)
- between numbers and letters within an electron configuration
- between elements and oxidation numbers
- between the elements and en dashes of a bond
- "on either side of a slash (/)" (ACS, p. 219)
- between elements and their physical states in parentheses (ACS, p. 272)
Be sure the spaces are consistently included or not included within a given document.
Elements and Numbers
Naming and capitalizing of elements and compounds: Spelled-out names of chemical elements and compounds should be lowercase and in roman.
Examples:
calcium, ozone, sulfuric acid
Abbreviations for chemical elements and compounds should be capitalized and should not have periods.
Examples:
NaCl, CO2, CaCO3
When dealing with compounds, or multiple elements combined together, take note of capitalization, since this differentiates between each individual element. For instance, there is a significant difference between Co (cobalt) and CO (carbon monoxide).
Subscripts and superscripts general rule: Pay special attention to the formatting of numerals within formulas and next to elements. Numbers in subscript, superscript, and regular font can all have different meanings. All numerals generally should be formatted in roman and should always maintain the same font size as the rest of the text in the formula. Refrain from using a smaller font size to indicate subscripts. Use the formatting tools within your word processor to create subscripts and superscripts.
Coefficients in formulas: A coefficient is the numeral in front of an element or compound that indicates what it is being multiplied by. Use regular font, not superscript or subscript formatting (e.g., 6NaOH) (ACS, p. 272). Spaces are not required between each of these characters.
Subscript numerals in formulas: Use subscripts for the numeral following an element to represent the amount of atoms present (e.g., C6H5CH3) (ACS, p. 263). See the following example for what coefficients and subscripts should look like together in a formula: 2Na3AlO3. Spaces are not required between each of these characters.
Ionic charges (superscripts to the right): A superscript plus or minus sign following an element indicates an ionic charge (e.g., Na+). If a numeral immediately precedes this symbol, it must be in superscript and come right after the element (e.g., Ca2+). Know that the number for the ionic charge is different from the number of atoms an element may have, which should be formatted in subscript and be before the superscripted ionic charge, if there is one in the formula (e.g., NO3–). If both the superscript and subscript numerals are present, be sure they are staggered and not stacked on top of each other (correct formatting: PO43–) (ACS, p. 262). Spaces are not required between each of these characters.
Isotopes (superscripts to the left): There are a couple of ways to format isotopes. Isotopes are often indicated by a superscript numeral hovering to the left of an element symbol (e.g., 14C). Isotopes may also be represented by the full name of an element, followed by a hyphen and the mass number, which should be in regular font, not superscript. (e.g., carbon-14). Spaces are not required between each of these characters. Note that an isotope is called by the symbol or name first followed by the numeral. So for example, 3H is pronounced H3, and the article an should precede it to correspond with the letter h (ACS, pp. 263–264).
Mass number and atomic numbers (sub/superscripts to the left): Mass numbers are indicated by a superscript numeral hovering to the left of an element symbol (e.g., 32S), which is the same format for an isotope. The atomic number, however, is formatted in subscript and should be to the left of the element (e.g., 6C) (ACS, pp. 261–262). Spaces are not required between each of these characters.
Electronic configuration (letters s, p, d, and f): "Name electron subshells and atomic orbitals with the lowercase roman letters s, p, d, and f" (ACS, p. 256). The numerals indicating the amount of electrons in the orbital, immediately following the letters, should be formatted in superscript. The numerals in front of the letters, indicating principal energy levels, must be in regular font (e.g., 3d44s4p2). Spaces are not required between each of these characters.
Oxidation numbers (elements with roman numerals): There are a couple of ways to format oxidation numbers. They may be formatted in superscript roman numerals and placed to the right of the element (e.g., CoIII). Additionally, these numbers may be regularly formatted roman numerals in parentheses to the right of the element, which could be spelled out or abbreviated to a symbol.
Examples:
cobalt(III) or Co(III)
Spaces are not required between each of these characters (ACS, pp. 262–263).
Other Symbols
Arrows in reactions: The preferred symbol for arrows is →. You may use your word processor to create this character, or consider copying and pasting the symbol from this wiki. Avoid adding an image or grouping together dashes and carets as such: -->. If this arrow symbol cannot be created, make sure that the same format for the arrow is consistently used across a document. There should be a nonbreaking space before and after the arrow since this is treated like a term in an equation.
Example:
Cr(CO)4 + CO → Cr(CO)5
Bonds: "When necessary for the discussion, indicate bonds by en dashes" (e.g., the C–C–C angle, carbon–oxygen bond) (ACS, p. 267). Spaces are not required between each of these characters.
Multiplication sign: Avoid using the asterisk sign (*) (ACS, p. 211) or the center dot (·) for multiplication. Note that these symbols often have other meanings in the context of chemistry. The times symbol (×) is usually appropriate in chemistry contexts. Be sure not to use the roman x symbol. Rather, use the specified Word symbol × (ALT+0215), or type × if you are using HTML. Also remember to insert a nonbreaking space on each side of the multiplication symbol when seen in an expression.
Formatting other common symbols: For concerns on how to format common chemistry symbols that may appear for physical quantities, consult appendix 13-1 on pages 277–283 within the ACS Style Guide. Pages 212–213 also give guidance on when to use italics or roman formatting for these symbols.
Abbreviations
Abbreviated compound units: When formatting abbreviated compound units (shortened units of measurement combined together), use a center dot (·) to represent multiplication (ACS, p. 224). Do not include any spaces on either side of the slash mark, if there is one.
Examples:
J/(mol·K), J/(kg·K).
Abbreviations (aq), (s), (l), (g): "To indicate the aqueous, solid, liquid, or gas state, use the appropriate abbreviations on the line, in parentheses, and with no space preceding them" (ACS, p. 272). Do not italicize these abbreviations; format them in roman.
Example:
Ag(s) + H+(aq) + Cl–(aq) → AgCl(s) + ½H2(g).
Miscellaneous
periodic table: Do not capitalize periodic table. Also, do not capitalize group, even if the group's number is next to it. Be sure to use a numeral when talking about a group number.
