Learn Hardcore Japanese: syuumatu ni tukue no ue wo katadukemasu.

The particle に marks a specific point in time. When you say 週末に, you mean “on the weekend.” Without に, 週末 is just a noun (“weekend”) and doesn’t clearly function as a time adverbial.

Can I omit に after 週末? Would it still be correct?

In casual speech, time expressions like 週末 can sometimes stand alone as adverbials (e.g. 週末行く “I’ll go on the weekend”). However:
• Leaving out に makes the sentence less precise or more casual.
• In polite or written Japanese, you almost always include に to avoid ambiguity.

What does 机の上 literally mean and why use の?

机の上 literally translates to “desk’s top.” The particle の links two nouns, showing a relationship often like possession or location. Here it means “the surface (上) of the desk (机).”

Why is を placed after 上 and what exactly is the object of the verb?

The particle を marks the direct object of the verb 片付けます. In this sentence, 机の上 (the desktop surface) is what you are tidying up. So you place を after 上 to show “I tidy up the desk’s top.”

Could I say 机を片付けます instead? How does that change the meaning?

Yes, 机を片付けます is grammatically correct, but it generally means “I tidy up the desk as a whole” (including drawers, legs, etc.). 机の上を片付けます is more specific: “I’m only tidying up what’s on top of the desk.”

What’s the difference between 片付けます and 掃除します?

• 片付けます (katazukemasu) means “to tidy up” or “to put things in order.” It focuses on clearing away clutter.
• 掃除します (souji shimasu) means “to clean” (e.g. dusting, vacuuming, wiping). It focuses on removing dirt.
You might first 片付ける (put books away) and then 掃除する (vacuum the floor).

Why is there no subject in this sentence? Who is doing the action?

Japanese often omits the subject when it’s understood from context. Here, it’s naturally “I” (or “we,” if you prefer), because you’re talking about your own plans. If you needed to specify, you could say 私は週末に机の上を片付けます.

What is the form of 片付けます, and what tense or politeness level is it?

片付けます is the polite non-past form of 片付ける. It can express either a habitual action (“I tidy up”) or a future plan (“I will tidy up”). In this context, it’s a plan for the weekend.

What is the typical word order in this sentence? Why is the time phrase first?

Japanese word order is generally:

Time (when) → 週末に
Topic/Subject (often omitted)
Location (where) → 机の上を
Object (what) → (here it’s folded into location)
Verb (action) → 片付けます
Putting the time phrase first is natural in Japanese: you establish when before saying what you do.

Does 週末 refer to a specific weekend or weekends in general?

週末 without any modifier usually means “this coming weekend” or the nearest weekend. If you want to talk about weekends in general, you might say 週末には with a nuance of “whenever it’s a weekend” or 週末ごとに (“every weekend”).