pattern - What is a Dotted Word™?

_{This is based on the What is a Word/Phrase™ series of Phrase™ and Word™ puzzles, started by JLee.}

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If a word follows a certain rule, then I call it a Dotted Word™.

Use the example word lists below to find the rule. Each word can be tested for whether it is a Dotted Word™ without depending on other words in these lists.

Dotted Word™, Not Dotted Word™
ONLINE, DIGITAL
HOWDY, HEY
URGES, INSTINCTS
NASAL, BARITONE
FROG, TOAD
POLAND, UKRAINE
WATER, LUBRICATE

FOLIO, DOCUMENT
COBRAS, PYTHONS
REBIND, UNSEAL
PRATTLER, BABBLER
LUAU, FIESTA
RECEPT, RECEIVING
KNIFE, SPOON
FRAMES, BOXES
LANDLADY, DUCHESS

Hint:

The number of possible Dotted Words™ is relatively small.

Hint 2:

This is a very elementary puzzle. You don't need more than one hint.

Answer

The last hint and also Gareth's answer make it clear that ...

... all Dotted Words can be split into symbols for chemical elements. But this is not a sufficient condition, because some of the non-dotted words, but not all, can also be "elementarily split".

The distinguishing trait is ...

... that all elements used in the dotted words must be of the same period, i.e. they must occur on the same row in the periodic table:

O·N·Li·Ne: Oxygen (8), Nitrogen (7), Lithium (3), Neon (10): period 2
Ho·W·Dy: Holmium (67), Tungsten (74), Dysprosium (66): period 6
U·Rg·Es: Uranium (92), Roentgenium (111), Einsteinium (99): period 7
Na·S·Al: Sodium (11), Sulfur (16), Aluminium (13): period 3
Fr·Og: Francium (87), Oganesson (118): period 7

Po·La·Nd: Polonium (84), Lanthanum (57), Neodymium (60): period 6
W·At·Er: Tungsten (74), Astatine (85), Erbium (68): period 6
F·O·Li·O: Fluorine (9), Oxygen (8), Lithium (3), Oxygen (8): period 2
Co·Br·As: Cobalt (27), Bromine (35), Arsenic (33): period 4
Re·Bi·Nd: Rhenium (75), Bismuth (83), Neodymium (60): period 6
Pr·At·Tl·Er: Praseodymium (59), Astatine (85), Thallium (81), Erbium (68): period 6
Lu·Au: Lutetium (71), Gold (79): period 6
Re·Ce·Pt: Rhenium (75), Cerium (58), Platinum (78): period 6
K·Ni·Fe: Potassium (19), Nickel (28), Iron (26): period 4
Fr·Am·Es: Francium (87), Americium (95), Einsteinium (99): period 7

La·Nd·La·Dy: Lanthanum (57), Neodymium (60), Lanthanum (57), Dysprosium (66): period 6

(There are several possible divisions for some words, but only one that makes it count as a Dotted Word.)

Why are they called Dotted Words?

No, it has nothing to do with Lewis dots, which would describe the electron configuration in an atom and therefore would refer to the columns in the periodic table.

They are called Dotted words, because some people call a dot a period.