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Unit 20 Chemistry

Chemistry uses a system of rules for naming and interpreting substances according to what atoms they include.


A chemical element contains one type of atom. Its chemical symbol consists of either one capital letter or one capital letter followed by one lowercase letter.


Hydrogen: H

Carbon: C

Oxygen: O

Chlorine: Cl

Sodium (natrium): Na

Iron (ferrum): Fe

Tin (stannum): Sn


A chemical compound is formed by combining more than one element. For example, table salt is Sodium (Na) and chloride (Cl) and is written NaCl. Notice that each element symbols retains its form and does not alter the capitalization.




Another example is Calcium oxide is Calcium (Ca) and Oxide (O) and is written CaO.




You will remember from Unit 1, that whole word capitalization is not used in Nemeth Code. Each capitalized letter requires its own capitalization.





(p.s. That is a lowercase "L" not an uppercase "i")



Nemeth Code or UEB

Chemical words, abbreviations and acronyms that appear in a narrative text do not require Nemeth Code switching. Punctuation, typeform, and spacing follow UEB rules.


Two hydrogens and one oxygen make water.


Skin cream often contains AHA or BHA.


Switch to Nemeth Code

When the words are replaced with their chemical symbols, they are no longer considered words; they are considered technical text and therefore rules for punctuation, typeform, spacing, the non-use of grade 2 contractions, and Nemeth Code switch indicators are followed.


Two hydrogens and one oxygen make (code switch) H2O (code switch).


H+H+O = H20



A subscript number after an element symbol specifies the number of atoms in a compound. You will remember that in Nemeth code, the subscript indicator is not used when the baseline character is a letter and the subscript is numeric. The subscript number (without a number indicator) follows the letter and remains on the baseline level.


Water: H20


Sugar: C6H12O6



A superscript plus or minus that follows a chemical symbol specifies the charge of ions (negative or positive) of an atom. A number before the plus or minus indicates the level of the charge. Sometimes in print more than one + or – will appear in a row. In braille, use the appropriate number followed by the + or – charge. If the charge is one, list the + or – without any number. If the superscript is not followed by a space, a baseline indicator is needed to return it to baseline level.






Note that the superscript "+" means positive, not a plus sign.

* Notice that the multipurpose indicator is used to return to base level before the sign of operation.


When a chemical group appears more than once in a chemical compound, they are put in parentheses. These must be placed within Nemeth Code indicators and enclosed in Nemeth Code parentheses. A subscript after the closing parenthesis tells how many times the chemical group appears in the compound. A subscript indicator is required because it is not directly after a letter.






* Notice that the subscript indicator is not needed after the letter "O", but it is required after the parenthesis.

A Roman numeral enclosed in parentheses indicates an ion’s positive charges. It appears unspaced from the element’s name.


Iron(II) also written as Fe2+


Lead(IV) also Pb4+


Isotope Notation (Subscripts and superscripts in front of an element)

In order to identify different isotypes of an element, subscripts and superscripts are added to the left side, or in front, of the element’s symbol. The atomic number is written as subscript and the mass number is written as superscript. In print the numbers appear one on top of the other.

In braille, the subscript indicator and atomic number are listed first, followed by the superscript indicator mass number. A baseline indicator is used to return to baseline before the chemical symbol.


Carbon-14: 14 6 C


Synthetic Uranium: 232 92 U



Chemical formulas often contain Greek letters or different typefaces within the same expression. Often quantities and variables are italicized, and other numbers or letters may be bold for particular emphasis. Braille typeforms must follow print typeface and, like capitalization, each letter, number or other symbol requires its own typeform indicator.

*Remember, when a letter is modified by a typeform, the ELI must be used, and when a number is modified by a typeform, the Numeric Indicator must be used.


Ionization Energy Equation





E = mc2


Energy: 4.184 J = 1 cal


C = λν


Arrows as Sign of Comparison

These two examples use the arrow symbol as a sign of comparison.

2H2+O2 2H2O


Zn+H+ Zn2++H2



Chemical expressions that cannot be brailled on one line have to be divided between two or more lines. (Refer to Unit 12: Rules for Runovers)

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