Learn Hardcore Greek: Το πάτωμα σφουγγαρίζεται κάθε Τετάρτη.

Here, the important information is the routine: that the floor gets mopped every Wednesday. Who does it (the cleaner, a family member, etc.) is not important, so the passive sounds natural.

Active vs passive:

Κάποιος σφουγγαρίζει το πάτωμα κάθε Τετάρτη.
= Someone mops the floor every Wednesday. (Active, with an explicit “someone”)
Το πάτωμα σφουγγαρίζεται κάθε Τετάρτη.
= The floor is mopped every Wednesday. (Passive, more neutral and natural here)

The Greek sentence works just like the English one: “The floor is mopped every Wednesday.”

How is σφουγγαρίζεται formed from σφουγγαρίζω?

The verb σφουγγαρίζω (to mop) forms its present non‑active (passive) voice with the ending ‑ομαι / ‑εται.

Present active (doing the action):

εγώ σφουγγαρίζω – I mop
εσύ σφουγγαρίζεις – you mop
αυτός/αυτή/αυτό σφουγγαρίζει – he/she/it mops

Present non‑active (receiving the action):

εγώ σφουγγαρίζομαι – I am mopped / I get mopped (theoretically)
εσύ σφουγγαρίζεσαι – you are mopped
αυτός/αυτή/αυτό σφουγγαρίζεται – he/she/it is mopped

So you can see:

stem: σφουγγαρίζ‑
passive ending (3rd sg): ‑εται

→ σφουγγαρίζεται.

What does το πάτωμα tell me about gender and number?

Το πάτωμα means “the floor”.

το is the neuter definite article (singular, nominative/accusative).
πάτωμα is a neuter noun, singular.

So:

το πάτωμα = the floor (one floor)
τα πατώματα = the floors (plural)

This is why the verb is 3rd person singular:
Το πάτωμα σφουγγαρίζεται… = The floor is mopped…

Could the sentence be plural, like “The floors are mopped every Wednesday”? How would that look?

Yes. With a plural subject, everything agrees in number:

Τα πατώματα σφουγγαρίζονται κάθε Τετάρτη.
= The floors are mopped every Wednesday.

Changes:

το πάτωμα → τα πατώματα (neuter plural)
σφουγγαρίζεται → σφουγγαρίζονται (3rd person plural non‑active)

Where can I put κάθε Τετάρτη in the sentence? Is the current word order fixed?

Greek word order is flexible. All of these are correct and natural:

Το πάτωμα σφουγγαρίζεται κάθε Τετάρτη.
Κάθε Τετάρτη το πάτωμα σφουγγαρίζεται.
Το πάτωμα κάθε Τετάρτη σφουγγαρίζεται. (a bit more marked in style)

The most neutral are:

Το πάτωμα σφουγγαρίζεται κάθε Τετάρτη.
Κάθε Τετάρτη το πάτωμα σφουγγαρίζεται.

Putting κάθε Τετάρτη first slightly emphasizes the time (“As for every Wednesday, the floor is mopped then”). Leaving it at the end feels very similar to English: “is mopped every Wednesday”.

Why is there no article before Τετάρτη? Could I say κάθε την Τετάρτη?

With κάθε (every), Greek does not use the article:

κάθε Τετάρτη = every Wednesday
κάθε μέρα = every day
κάθε μήνα = every month

So:

✅ κάθε Τετάρτη
❌ κάθε την Τετάρτη (incorrect)

If you remove κάθε, you can use the article:

Την Τετάρτη σφουγγαρίζεται το πάτωμα.
= On Wednesday the floor is mopped.

That talks about this/that Wednesday (more specific), not a regular every Wednesday habit.

Why is Τετάρτη capitalized? Are days of the week usually written with a capital in Greek?

In standard modern Greek spelling, days of the week are normally written with a lowercase initial, unless they start the sentence:

κάθε τετάρτη (standard spelling)
τη Δευτέρα, την τρίτη, etc.

In practice, especially in material for learners or under English influence, you will also see them capitalized, as in your sentence:

κάθε Τετάρτη

So:

τετάρτη / Τετάρτη – form of the word
Capital vs lowercase is mostly an orthographic convention; it doesn’t change the grammar or meaning.

Does this Greek sentence mean more “is mopped” or “gets mopped”? Is it about a habit?

Σφουγγαρίζεται here is present tense, and combined with κάθε Τετάρτη it clearly expresses a habitual/repeated action.

Natural English equivalents:

The floor is mopped every Wednesday.
The floor gets mopped every Wednesday.

Both capture the same idea. Greek just uses the plain present passive:

σφουγγαρίζεται = is mopped / gets mopped (regularly, in this context)

Can I say this in the active voice? For example, “I mop the floor every Wednesday” in Greek?

Yes. Active voice is completely fine; you just have to name the subject.

Examples:

Σφουγγαρίζω το πάτωμα κάθε Τετάρτη.
= I mop the floor every Wednesday.
Η καθαρίστρια σφουγγαρίζει το πάτωμα κάθε Τετάρτη.
= The cleaner mops the floor every Wednesday.
Σφουγγαρίζουν το πάτωμα κάθε Τετάρτη.
= They mop the floor every Wednesday. (impersonal “they”)

The original sentence simply leaves the doer out and focuses on the action done to the floor.

What is the difference between σφουγγαρίζω and more general verbs like καθαρίζω?

σφουγγαρίζω = to mop, specifically with a mop (or technically with a sponge).
It comes from σφουγγάρι = sponge.
καθαρίζω = to clean (general verb, any method).

So:

σφουγγαρίζω το πάτωμα. = I mop the floor.
καθαρίζω το πάτωμα. = I clean the floor. (could be sweeping, mopping, etc.)

In your sentence, σφουγγαρίζεται tells you how it’s cleaned: with a mop.

How do you pronounce Το πάτωμα σφουγγαρίζεται κάθε Τετάρτη?

Approximate pronunciation (stressed syllables in CAPS):

Το ΠΆ‑τω‑μα σφουγ‑γα‑ΡΊ‑ζε‑ται ΚΆ‑θε τε‑ΤΆρ‑τη

In IPA:

Το – [to]
πάτωμα – [ˈpatoma]
σφουγγαρίζεται – [sfuŋɡaˈrizete]
- γγ before α is pronounced like ng + g ([ŋɡ])
κάθε – [ˈkaθe] (θ like English th in think)
Τετάρτη – [teˈtarti]

So the whole sentence:
[to ˈpatoma sfuŋɡaˈrizete ˈkaθe teˈtarti]

How would I negate this sentence: “The floor is not mopped every Wednesday”?

You simply place δεν before the verb:

Το πάτωμα δεν σφουγγαρίζεται κάθε Τετάρτη.
= The floor is not mopped every Wednesday.

Pattern:

[subject] + δεν + [verb] + [rest]

So you keep everything else the same; you just add δεν right before σφουγγαρίζεται.