Learn Hardcore Portuguese (Portugal): O detergente cheira bem, e o aspirador novo é silencioso. - The detergent smells good, and the new vacuum cleaner is quiet.

Usually no. Portuguese typically doesn’t use a comma before e when it simply links two clauses. A comma can appear if you want to mark a pause or clearly separate two independent clauses with different subjects. Here, it’s optional. Most editors would write:

O detergente cheira bem e o aspirador novo é silencioso.

Why is it cheira bem and not cheira bom?

Because bem is an adverb modifying the verb cheirar. In Portuguese, when you say something “smells good/bad,” you use adverbs: cheira bem (smells good), cheira mal (smells bad).

Use bom/mau (adjectives) with nouns: cheiro bom/cheiro mau (a good/bad smell).
You can also say: tem um cheiro bom/agradável (it has a good/pleasant smell).
If you want to say it smells like something good: cheira a bom café (it smells like good coffee).

What’s the difference between cheirar, cheirar a, and cheiro?

cheirar (intransitive): describes emitting a smell. Example: O detergente cheira bem.
cheirar a + noun: “to smell like/of.” Example: Cheira a limão. (It smells like lemon.)
cheirar + object (transitive): “to sniff/smell” something actively. Example: Cheira o detergente. (Smell the detergent.)
cheiro (noun): “smell/scent.” Example: O cheiro do detergente é agradável.

Why o detergente and o aspirador? Are these nouns masculine?

Yes. detergente and aspirador are masculine in European Portuguese, so they take o in the singular and os in the plural:

Singular: o detergente, o aspirador
Plural: os detergentes, os aspiradores Indefinite forms: um detergente, um aspirador

Why is the adjective novo after the noun (o aspirador novo)? Can it go before?

Both positions are possible, but the meaning shifts slightly:

o aspirador novo (post-nominal): literally new (brand-new/unused) or newly acquired.
o novo aspirador (pre-nominal): often “the new/different replacement” (new to you compared to the old one), a bit more subjective or contrastive. Context often makes the nuance clear.

Why silencioso and not silenciosa? How does agreement work?

Adjectives agree with the noun in gender and number. aspirador is masculine singular, so:

Masculine singular: silencioso
Feminine singular (e.g., a máquina): silenciosa
Masculine plural: silenciosos
Feminine plural: silenciosas

Why é silencioso and not está silencioso?

ser expresses an inherent or typical characteristic: O aspirador é silencioso = this model/type is quiet by design.
estar expresses a temporary state: O aspirador está silencioso could mean “it’s quiet right now” (e.g., it’s off, or unusually quiet at the moment).

What’s the opposite of silencioso?

barulhento (noisy). Example: Este aspirador é barulhento.

Is aspirador the usual word in Portugal? I’ve seen aspirador de pó.

In Portugal, aspirador on its own is the standard word for a vacuum cleaner. In Brazil, aspirador de pó is very common. In Portugal you can also hear aspirador de pó, but it’s not necessary.

Does detergente mean dish soap or laundry detergent in Portugal?

detergente is a general term. To be specific:

Dishwashing liquid: detergente da loiça / detergente para a loiça
Laundry detergent: detergente da roupa Context usually clarifies which one you mean.

How would this sentence look in the plural?

Os detergentes cheiram bem e os aspiradores novos são silenciosos. Notes:
cheiram (they smell) — plural of cheirar
são (they are) — plural of ser
aspiradores novos / silenciosos — adjectives and nouns agree in number.

Can I drop the second article and say: O detergente cheira bem e aspirador novo é silencioso?

No. In coordinated independent clauses with different subjects, you keep the article before each subject. You need o before aspirador:

Correct: O detergente cheira bem e o aspirador novo é silencioso.

Is there a simple rule to remember bem vs bom?

bem = adverb (how something happens/is perceived): cheira bem, sabe bem (tastes good), corre bem (goes well).
bom/boa = adjective (describes a noun): um cheiro bom, um detergente bom, uma ideia boa. Opposites: mal (adverb) and mau/má (adjective): cheira mal; um cheiro mau.

What’s another way to say “smells good”?

Cheira bem (most natural, everyday)
Tem um cheiro agradável (more descriptive/formal)
With specifics: Cheira a flores, Cheira a lavanda, Cheira a limpo (“smells clean”)

Any quick pronunciation tips for these words in European Portuguese?

detergente: de-ter-JEN-te. Final “e” is reduced; “g” before “e” sounds like the “s” in “measure.”
cheira: SHEY-rah. ch = “sh”; ei like “ey” in “they.”
bem: bayng (nasal “em” at the end; don’t fully pronounce the “m”).
aspirador: uh-spee-rah-DOR (stress on the last syllable; flap the “r” between vowels).
novo: NOH-voo (clear “v,” not “b”).
é: open “eh” sound.
silencioso: si-len-see-OH-zoo (the “c” before “i” is “s”; stress on “o-so”).