Question

identify the formula units for each particle. not all units will be used, some will be used more than once.
n₂
srcl₂
ca
no
moles molecules formula units atoms

Explanation:

Step1: Analyze \( \text{N}_2 \)

\( \text{N}_2 \) is a molecular compound (diatomic gas), so its formula unit can be molecules (since it exists as discrete molecules) and also moles (amount of substance). But for the particle type, \( \text{N}_2 \) particles are molecules. Also, moles can be used for amount, but the options for particle units: \( \text{N}_2 \) is a molecule, so it can be molecules, and also moles (but the options given are moles, molecules, formula units, atoms). Wait, actually, for molecular compounds, the formula unit is a molecule. So \( \text{N}_2 \): molecules (and moles, but let's match the particle type). Wait, the question is "formula units for each particle". Wait, maybe the options are the units to assign. Let's recall:

- Atoms: for elemental substances that are atoms (like Ca, which is a metal, exists as atoms in metallic structure, or as individual atoms in terms of particle).
- Molecules: for molecular compounds (like \( \text{N}_2 \), \( \text{NO} \)) which exist as discrete molecules.
- Formula units: for ionic compounds (like \( \text{SrCl}_2 \)) which exist as a lattice of ions, so the formula unit is the simplest ratio (formula unit), not a molecule.
- Moles: is an amount unit, but maybe the question is about the type of particle. Wait, maybe the options are the type of particle unit. Let's re-express:

1. \( \text{N}_2 \): it's a diatomic molecule, so its particle is a molecule. Also, moles can be used, but the particle type (like what the formula represents as a particle) – \( \text{N}_2 \) is a molecule, so molecules.
2. \( \text{SrCl}_2 \): it's an ionic compound (strontium chloride), so the formula unit is a formula unit (since it's a lattice, not discrete molecules).
3. \( \text{Ca} \): it's a metal, exists as atoms (in metallic structure), so its particle is an atom.
4. \( \text{NO} \): it's a molecular compound (nitric oxide), so its particle is a molecule.

Wait, but also, moles is an amount unit, but maybe the question is assigning the correct particle unit (molecules, formula units, atoms) and moles is a unit of amount, but maybe the options are the types of particles. Wait, let's correct:

- \( \text{N}_2 \): molecules (since it's a molecular substance, exists as \( \text{N}_2 \) molecules)
- \( \text{SrCl}_2 \): formula units (since it's ionic, exists as a lattice, so the formula unit is \( \text{SrCl}_2 \) formula unit)
- \( \text{Ca} \): atoms (since calcium is a metal, its particles are atoms)
- \( \text{NO} \): molecules (since it's a molecular compound, exists as \( \text{NO} \) molecules)

Also, moles can be used for any substance (amount of substance), but maybe the question is about the type of particle (molecules, formula units, atoms) and moles is a unit of amount, but perhaps the options include moles as a possible unit (like the amount of \( \text{N}_2 \) can be in moles, but the particle type is molecule). Wait, maybe the question is to assign each compound to the correct particle unit (moles, molecules, formula units, atoms). Let's clarify:

- \( \text{N}_2 \): is a molecule, so its particle is a molecule; also, the amount can be in moles. But the options are the units to assign. Let's go step by step.

Step2: Assign \( \text{N}_2 \)

\( \text{N}_2 \) is a molecular substance, so the particle is a molecule. So assign to molecules. Also, moles can be used, but let's check the other compounds.

Step3: Assign \( \text{SrCl}_2 \)

\( \text{SrCl}_2 \) is an ionic compound (strontium is a metal, chlorine is a non-metal), so it exists as a crystal lattice of \( \text{Sr}^{2+} \) and \( \text{Cl}^- \) ions. The formula unit is the simplest ratio ( \( \text{SrCl}_2 \) ), so the particle unit is formula units.

Step4: Assign \( \text{Ca} \)

\( \text{Ca} \) is a metal, which exists as atoms (in the metallic structure, or as individual atoms in terms of the particle). So the particle unit is atoms.

Step5: Assign \( \text{NO} \)

\( \text{NO} \) is a molecular compound (nitrogen monoxide), so it exists as discrete \( \text{NO} \) molecules. So the particle unit is molecules.

Also, moles is a unit of amount, so each substance can be measured in moles (amount of substance), but the question is about the formula units for each particle (the type of particle). Wait, maybe the options are the units to connect. Let's list the connections:

- \( \text{N}_2 \): molecules (and moles, but let's see the options)
- \( \text{SrCl}_2 \): formula units (and moles)
- \( \text{Ca} \): atoms (and moles)
- \( \text{NO} \): molecules (and moles)

But the options given are moles, molecules, formula units, atoms. Wait, maybe each compound can be associated with moles (as amount), but the particle type:

- \( \text{N}_2 \): molecules (particle)
- \( \text{SrCl}_2 \): formula units (particle, since it's ionic)
- \( \text{Ca} \): atoms (particle)
- \( \text{NO} \): molecules (particle)

Also, moles is a unit of amount, so maybe all can be associated with moles, but the question is "formula units for each particle" – maybe the correct assignments are:

- \( \text{N}_2 \): molecules (and moles)
- \( \text{SrCl}_2 \): formula units (and moles)
- \( \text{Ca} \): atoms (and moles)
- \( \text{NO} \): molecules (and moles)

But let's check standard definitions:

- **Atoms**: Used for elemental substances that are monatomic (like Ca, which is a metal, exists as atoms in the metallic lattice, so the particle is an atom).
- **Molecules**: Used for molecular compounds (like \( \text{N}_2 \), \( \text{NO} \)) which exist as discrete molecules.
- **Formula units**: Used for ionic compounds (like \( \text{SrCl}_2 \)) which exist as a lattice of ions, so the formula unit is the simplest ratio (not a molecule).
- **Moles**: Is a unit of amount (mol), so any substance can be measured in moles (amount of substance), but the question is about the type of particle (what the formula represents as a particle).

So the correct connections:

- \( \text{N}_2 \) → molecules (and moles)
- \( \text{SrCl}_2 \) → formula units (and moles)
- \( \text{Ca} \) → atoms (and moles)
- \( \text{NO} \) → molecules (and moles)

But since the options include moles, maybe moles is a common unit for amount, but the particle type:

Wait, maybe the question is asking for the type of particle (atom, molecule, formula unit) and moles as amount. Let's proceed with the standard:

1. \( \text{N}_2 \): It's a diatomic molecule, so the particle is a molecule. So connect \( \text{N}_2 \) to molecules.
2. \( \text{SrCl}_2 \): It's an ionic compound, so the particle is a formula unit (since it's a lattice, not a molecule). Connect \( \text{SrCl}_2 \) to formula units.
3. \( \text{Ca} \): It's a metal, exists as atoms (in the metallic structure), so the particle is an atom. Connect \( \text{Ca} \) to atoms.
4. \( \text{NO} \): It's a molecular compound (nitric oxide), so the particle is a molecule. Connect \( \text{NO} \) to molecules.

Also, moles can be used for all (amount of substance), but the question is about the formula units for each particle (the type of particle). So:

- \( \text{N}_2 \): molecules
- \( \text{SrCl}_2 \): formula units
- \( \text{Ca} \): atoms
- \( \text{NO} \): molecules

And moles is a unit of amount, so maybe each can also be connected to moles, but the primary particle type:

So the connections:

- \( \text{N}_2 \): molecules (and moles)
- \( \text{SrCl}_2 \): formula units (and moles)
- \( \text{Ca} \): atoms (and moles)
- \( \text{NO} \): molecules (and moles)

But since the options are moles, molecules, formula units, atoms, we can assign:

- \( \text{N}_2 \): molecules (and moles, but let's pick the particle type)
- \( \text{SrCl}_2 \): formula units
- \( \text{Ca} \): atoms
- \( \text{NO} \): molecules

And moles is a unit of amount, so maybe all can be connected to moles as well, but the question is "formula units for each particle" – maybe the intended answers are:

- \( \text{N}_2 \): molecules
- \( \text{SrCl}_2 \): formula units
- \( \text{Ca} \): atoms
- \( \text{NO} \): molecules

And moles is a common unit for amount, so perhaps:

- \( \text{N}_2 \): molecules (and moles)
- \( \text{SrCl}_2 \): formula units (and moles)
- \( \text{Ca} \): atoms (and moles)
- \( \text{NO} \): molecules (and moles)

But let's confirm:

- **Atoms**: Ca is a metal, so its particles are atoms (so Ca → atoms)
- **Molecules**: \( \text{N}_2 \) and \( \text{NO} \) are molecular compounds, so their particles are molecules (so \( \text{N}_2 \) → molecules, \( \text{NO} \) → molecules)
- **Formula units**: \( \text{SrCl}_2 \) is ionic, so its particle is a formula unit (so \( \text{SrCl}_2 \) → formula units)
- **Moles**: All substances can be measured in moles (amount of substance), so each can be connected to moles, but the question is about the type of particle (what the formula represents as a particle), so:

Final connections:

- \( \text{N}_2 \) → molecules
- \( \text{SrCl}_2 \) → formula units
- \( \text{Ca} \) → atoms
- \( \text{NO} \) → molecules

And moles can be connected to all (since moles is an amount unit), but the primary particle type.

Answer:

• \( \text{N}_2 \): molecules (and moles)
• \( \text{SrCl}_2 \): formula units (and moles)
• \( \text{Ca} \): atoms (and moles)
• \( \text{NO} \): molecules (and moles)

But based on the particle type (what the formula represents as a particle):

• \( \text{N}_2 \) is a molecule → molecules
• \( \text{SrCl}_2 \) is an ionic compound → formula units
• \( \text{Ca} \) is a metal (monatomic) → atoms
• \( \text{NO} \) is a molecule → molecules

(Note: Moles is a unit of amount, so all can also be associated with moles, but the question is about the formula units for each particle (the type of particle), so the above are the particle-type assignments.)