Cheap flights from Fayetteville to San Antonio (FAY - SAT) from $273

This is the cheapest round-trip flight price found by a Cheapflights user in the last 72 hours by searching for a flight departing on 5/8. Fares are subject to change and may not be available on all flights or dates of travel. Click the price to replicate the search for this deal.
FAY — SAT
Apr 23 — Apr 301

The best prices from Fayetteville to San Antonio are usually found in September or October, booked 16 days in advance, depart on a Saturday or Wednesday and return on a Tuesday

Cheap flight deals from Fayetteville to San Antonio

Discover tips and strategies to find the most affordable flight options for your journey from Fayetteville (FAY) to San Antonio (SAT). Learn about various techniques such as flexible date searches, comparing prices across and setting up price alerts. Use these methods to find the cheapest flights available for your travel needs. Data last updated April 18, 2024.

Popular in

January

Cheapest in

September

Average price

$480

Round-trip from

$288
High demand for flights, 32% potential price rise
Best time to find cheap flights, 30% potential price drop
Average for round-trip flights in April 2024
From Fayetteville to San Antonio

What is the cheapest day to fly round-trip from Fayetteville, North Carolina to San Antonio?

Travelers have found that booking a Friday departure is the best way to save up to 49% on the cost of booking your flights compared to booking on days of the week where this route is of high demand.

How far in advance should I book a flight from Fayetteville, North Carolina to San Antonio?

When searching for a good deal, it’s best to be prepared for potential fluctuations in price. We recommend booking at least 17 days in advance, which can save you up to 39% on flights from Fayetteville, North Carolina to San Antonio compared to booking the week you need them. Waiting 17 days out may not be for everyone, so we have options available for flights within the next two weeks, with the lowest price starting at $249. For sooner than that we have options available in the next 3 days from $249.

What is the cheapest month to fly from Fayetteville, North Carolina to San Antonio?

Flights from Fayetteville, North Carolina to San Antonio lean towards being more expensive in January. Prices are generally better when you fly from Fayetteville, North Carolina to San Antonio in September, with the cheapest ticket starting at $212.

When is the cheapest time to fly from Fayetteville, North Carolina to San Antonio (FAY - SAT)?

Unlike in the morning, when flights are generally more expensive, you can save up to 21% on flights from Fayetteville, North Carolina to San Antonio by exploring options for tickets in the evening.

Cheap American Airlines flights from Fayetteville to San Antonio

Explore cheap flight options specifically provided by American Airlines for the route between Fayetteville and San Antonio. Find affordable fares and compare prices with other airlines to secure the best deal for your journey. Over the last 7 days, Cheapflights users made 3,192,047 searches. Data last updated April 18, 2024.
Take a look at some of the lowest-priced American Airlines flights heading from Fayetteville to San Antonio. It's recommended that users confirm their flight details before booking.
Wed 5/87:00 amFAY - SAT
1 stop6h 10mAmerican Airlines
Mon 5/135:55 pmSAT - FAY
1 stop5h 06mAmerican Airlines
Deal found 4/17$273
Wed 5/85:16 amFAY - SAT
1 stop7h 54mAmerican Airlines
Mon 5/135:55 pmSAT - FAY
1 stop5h 06mAmerican Airlines
Deal found 4/18$343
Wed 5/84:08 pmFAY - SAT
2 stops8h 46mAmerican Airlines
Mon 5/135:55 pmSAT - FAY
1 stop5h 06mAmerican Airlines
Deal found 4/18$348
Wed 5/84:08 pmFAY - SAT
2 stops8h 46mAmerican Airlines
Mon 5/135:55 pmSAT - FAY
1 stop5h 06mAmerican Airlines
Deal found 4/17$358
Fri 4/268:23 pmFAY - SAT
1 stop4h 57mAmerican Airlines
Mon 4/295:56 pmSAT - FAY
1 stop5h 01mAmerican Airlines
Deal found 4/17$365
Fri 4/268:23 pmFAY - SAT
1 stop4h 57mAmerican Airlines
Mon 4/2910:52 amSAT - FAY
2 stops10h 17mAmerican Airlines
Deal found 4/17$370
Thu 5/308:32 pmFAY - SAT
1 stop4h 42mAmerican Airlines
Sun 6/25:55 pmSAT - FAY
1 stop5h 06mAmerican Airlines
Deal found 4/18$383
Fri 4/268:23 pmFAY - SAT
1 stop4h 57mAmerican Airlines
Sat 4/272:33 pmSAT - FAY
2 stops8h 24mAmerican Airlines
Deal found 4/17$415
Thu 7/116:40 amFAY - SAT
2 stops10h 04mAmerican Airlines
Tue 7/165:52 pmSAT - FAY
1 stop5h 06mAmerican Airlines
Deal found 4/17$418

Cheap Delta flights from Fayetteville to San Antonio

Explore cheap flight options specifically provided by Delta for the route between Fayetteville and San Antonio. Find affordable fares and compare prices with other airlines to secure the best deal for your journey. Over the last 7 days, Cheapflights users made 3,192,047 searches. Data last updated April 18, 2024.
Take a gander at the lowest prices we've found on Delta flights from Fayetteville to San Antonio. Check back soon if you're not seeing flights that suit your needs.
Sat 8/176:00 amFAY - SAT
1 stop6h 00mDelta
Sat 8/244:25 pmSAT - FAY
1 stop5h 37mDelta
Deal found 4/17$296
Thu 7/116:00 amFAY - SAT
1 stop4h 33mDelta
Tue 7/164:29 pmSAT - FAY
1 stop5h 25mDelta
Deal found 4/17$332
Tue 5/76:00 amFAY - SAT
1 stop4h 42mDelta
Wed 5/84:15 pmSAT - FAY
1 stop6h 11mDelta
Deal found 4/16$487
Fri 4/263:53 pmFAY - SAT
1 stop6h 59mDelta
Sat 4/275:00 pmSAT - FAY
1 stop5h 12mDelta
Deal found 4/17$492
Fri 4/263:53 pmFAY - SAT
1 stop6h 59mDelta
Sun 4/284:30 pmSAT - FAY
1 stop5h 42mDelta
Deal found 4/17$536
Tue 5/76:00 amFAY - SAT
1 stop4h 42mDelta
Wed 5/83:00 pmSAT - FAY
2 stops31h 26mDelta
Deal found 4/16$540
Tue 5/76:00 amFAY - SAT
1 stop4h 42mDelta
Wed 5/84:15 pmSAT - FAY
1 stop6h 11mDelta
Deal found 4/17$547
Tue 4/236:00 amFAY - SAT
1 stop4h 53mDelta
Thu 4/257:00 amSAT - FAY
1 stop7h 13mDelta
Deal found 4/17$897
Tue 4/236:00 amFAY - SAT
1 stop5h 55mDelta
Thu 4/255:15 amSAT - FAY
2 stops8h 58mDelta
Deal found 4/17$1,750

Cheap Fayetteville to San Antonio flights in April & May 2024

Find cheap flight options from Fayetteville to San Antonio specifically for the months of April and May 2024. Explore affordable fares based on user searches. Over the last 7 days, Cheapflights users made 3,192,047 searches. Prices were last updated on April 18, 2024.
The lowest fares we've come across on flights traveling from Fayetteville to San Antonio in April and May 2024. Check back in a little while for more flight options.
Wed 5/87:00 amFAY - SAT
1 stop6h 10mAmerican Airlines
Mon 5/135:55 pmSAT - FAY
1 stop5h 06mAmerican Airlines
Deal found 4/17$273
Wed 5/85:16 amFAY - SAT
1 stop7h 54mAmerican Airlines
Mon 5/135:55 pmSAT - FAY
1 stop5h 06mAmerican Airlines
Deal found 4/18$343
Wed 5/84:08 pmFAY - SAT
2 stops8h 46mAmerican Airlines
Mon 5/135:55 pmSAT - FAY
1 stop5h 06mAmerican Airlines
Deal found 4/18$348
Wed 5/84:08 pmFAY - SAT
2 stops8h 46mAmerican Airlines
Mon 5/135:55 pmSAT - FAY
1 stop5h 06mAmerican Airlines
Deal found 4/17$358
Fri 4/268:23 pmFAY - SAT
1 stop4h 57mAmerican Airlines
Mon 4/295:56 pmSAT - FAY
1 stop5h 01mAmerican Airlines
Deal found 4/17$365
Fri 4/268:23 pmFAY - SAT
1 stop4h 57mAmerican Airlines
Mon 4/2910:52 amSAT - FAY
2 stops10h 17mAmerican Airlines
Deal found 4/17$370
Thu 5/308:32 pmFAY - SAT
1 stop4h 42mAmerican Airlines
Sun 6/25:55 pmSAT - FAY
1 stop5h 06mAmerican Airlines
Deal found 4/18$383
Fri 4/268:23 pmFAY - SAT
1 stop4h 57mAmerican Airlines
Sat 4/272:33 pmSAT - FAY
2 stops8h 24mAmerican Airlines
Deal found 4/17$415
Fri 4/265:15 amFAY - SAT
2 stops9h 28mAmerican Airlines
Sun 4/284:28 pmSAT - FAY
2 stops6h 29mAmerican Airlines
Deal found 4/17$420

Fayetteville to San Antonio 2024 flight deals

Discover exclusive flight deals for travel between Fayetteville and San Antonio in 2024. Find excellent offers based on user searches. Over the last 7 days, Cheapflights users made 3,192,047 searches. Data last updated April 18, 2024.
The lowest fares we've come across on flights traveling from Fayetteville to San Antonio in April and May 2024. Check back in a little while for more flight options.
Wed 5/87:00 amFAY - SAT
1 stop6h 10mAmerican Airlines
Mon 5/135:55 pmSAT - FAY
1 stop5h 06mAmerican Airlines
Deal found 4/17$273
Sat 8/176:00 amFAY - SAT
1 stop6h 00mDelta
Sat 8/244:25 pmSAT - FAY
1 stop5h 37mDelta
Deal found 4/17$296
Thu 7/116:00 amFAY - SAT
1 stop4h 33mDelta
Tue 7/164:29 pmSAT - FAY
1 stop5h 25mDelta
Deal found 4/17$332
Wed 5/85:16 amFAY - SAT
1 stop7h 54mAmerican Airlines
Mon 5/135:55 pmSAT - FAY
1 stop5h 06mAmerican Airlines
Deal found 4/18$343
Wed 5/84:08 pmFAY - SAT
2 stops8h 46mAmerican Airlines
Mon 5/135:55 pmSAT - FAY
1 stop5h 06mAmerican Airlines
Deal found 4/18$348
Wed 5/84:08 pmFAY - SAT
2 stops8h 46mAmerican Airlines
Mon 5/135:55 pmSAT - FAY
1 stop5h 06mAmerican Airlines
Deal found 4/17$358
Fri 4/268:23 pmFAY - SAT
1 stop4h 57mAmerican Airlines
Mon 4/295:56 pmSAT - FAY
1 stop5h 01mAmerican Airlines
Deal found 4/17$365
Fri 4/268:23 pmFAY - SAT
1 stop4h 57mAmerican Airlines
Mon 4/2910:52 amSAT - FAY
2 stops10h 17mAmerican Airlines
Deal found 4/17$370
Thu 5/308:32 pmFAY - SAT
1 stop4h 42mAmerican Airlines
Sun 6/25:55 pmSAT - FAY
1 stop5h 06mAmerican Airlines
Deal found 4/18$383

Fayetteville to San Antonio flights leaving soon

Find last-minute flight options from Fayetteville to San Antonio for spontaneous travel. Discover available flights and compare prices based on user searches. Secure great deals and offers for spontaneous trips with quick booking options. Over the last 7 days, Cheapflights users made 3,192,047 searches. Data last updated April 18, 2024.
Have a look at some of the flights available from Fayetteville to San Antonio departing last-minute. Tip: verify your flight details before completing your reservation.
Fri 4/268:23 pmFAY - SAT
1 stop4h 57mAmerican Airlines
Mon 4/295:56 pmSAT - FAY
1 stop5h 01mAmerican Airlines
Deal found 4/17$365
Fri 4/268:23 pmFAY - SAT
1 stop4h 57mAmerican Airlines
Mon 4/2910:52 amSAT - FAY
2 stops10h 17mAmerican Airlines
Deal found 4/17$370
Fri 4/268:23 pmFAY - SAT
1 stop4h 57mAmerican Airlines
Sat 4/272:33 pmSAT - FAY
2 stops8h 24mAmerican Airlines
Deal found 4/17$415
Fri 4/265:15 amFAY - SAT
2 stops9h 28mAmerican Airlines
Sun 4/284:28 pmSAT - FAY
2 stops6h 29mAmerican Airlines
Deal found 4/17$420
Tue 4/237:00 amFAY - SAT
1 stop6h 16mAmerican Airlines
Thu 4/255:56 pmSAT - FAY
1 stop5h 01mAmerican Airlines
Deal found 4/17$449
Tue 4/237:00 amFAY - SAT
2 stops7h 43mAmerican Airlines
Thu 4/255:56 pmSAT - FAY
1 stop5h 01mAmerican Airlines
Deal found 4/17$454
Tue 4/237:00 amFAY - SAT
2 stops7h 43mAmerican Airlines
Thu 4/251:10 pmSAT - FAY
2 stops7h 59mAmerican Airlines
Deal found 4/17$459
Fri 4/263:53 pmFAY - SAT
1 stop6h 59mDelta
Sat 4/275:00 pmSAT - FAY
1 stop5h 12mDelta
Deal found 4/17$492
Fri 4/263:53 pmFAY - SAT
1 stop6h 59mDelta
Sun 4/284:30 pmSAT - FAY
1 stop5h 42mDelta
Deal found 4/17$536

Find flights from Fayetteville to San Antonio within your budget

Customize your flight search to find flights from Fayetteville to San Antonio that fit within your specific budget. Explore options based on user searches and filter the results based on your desired price range. Find flights that match your budget for a cost-effective journey. Over the last 7 days, Cheapflights users made 3,192,047 searches. Data last updated April 18, 2024.

Fly from

Any airport

Fly to

Any airport

Budget

$273 - $487

Route

Depart

Return

Price

FayettevilleSan Antonio

FAY - SAT

FAYSAT

Fayetteville

Wed 5/8

1 stop6h 10m

San Antonio

Mon 5/13

1 stop5h 06m

$273

FayettevilleSan Antonio

FAY - SAT

FAYSAT

Fayetteville

Sat 8/17

1 stop6h 00m

San Antonio

Sat 8/24

1 stop5h 37m

$296

FayettevilleSan Antonio

FAY - SAT

FAYSAT

Fayetteville

Thu 7/11

1 stop4h 33m

San Antonio

Tue 7/16

1 stop5h 25m

$332

FayettevilleSan Antonio

FAY - SAT

FAYSAT

Fayetteville

Wed 5/8

1 stop7h 54m

San Antonio

Mon 5/13

1 stop5h 06m

$343

FayettevilleSan Antonio

FAY - SAT

FAYSAT

Fayetteville

Wed 5/8

2 stops8h 46m

San Antonio

Mon 5/13

1 stop5h 06m

$348

FayettevilleSan Antonio

FAY - SAT

FAYSAT

Fayetteville

Wed 5/8

2 stops8h 46m

San Antonio

Mon 5/13

1 stop5h 06m

$358

FayettevilleSan Antonio

FAY - SAT

FAYSAT

Fayetteville

Thu 5/30

1 stop4h 42m

San Antonio

Sun 6/2

1 stop5h 06m

$383

FayettevilleSan Antonio

FAY - SAT

FAYSAT

Fayetteville

Thu 7/11

2 stops10h 04m

San Antonio

Tue 7/16

1 stop5h 06m

$418

FayettevilleSan Antonio

FAY - SAT

FAYSAT

Fayetteville

Tue 5/7

1 stop4h 42m

San Antonio

Wed 5/8

1 stop6h 11m

$487

Flights are sorted by cheapest first

Deals found on 4/17

When is the best time to book a flight from Fayetteville, North Carolina to San Antonio?

Use this chart to determine the optimal time to book a round-trip flight from Fayetteville to San Antonio. Price data was last updated on January 28, 2024.
The best time to book flights from Fayetteville, North Carolina to San Antonio is 16 days before your desired departure date. The cost of your flight will likely increase significantly if you book two weeks in advance of your flight.
Search Deals

When is the cheapest time to fly from Fayetteville, North Carolina to San Antonio?

Use this chart to determine the cheapest time to fly round-trip from Fayetteville to San Antonio. Price data was last updated on April 14, 2024.
Morning
Noon
Afternoon
Evening
All times are departure.
Travelers seeking maximum savings on their Fayetteville, North Carolina to San Antonio flight should consider departing on Saturday afternoons when fares are most often at their lowest. Tuesday at noon flights should be avoided if possible as fares are typically the most expensive at this time.
Search Deals

Average price of flights to San Antonio by month

Plan your trip from Fayetteville to San Antonio by taking into account the cheapest months to travel. The average price of a one-way flight from Fayetteville to San Antonio is currently $0 while a round-trip flight costs $360. Price data was last updated on April 14, 2024.

Currently, September is the cheapest month in which you can book a flight from Fayetteville, North Carolina to San Antonio (average of $288). Flying from Fayetteville, North Carolina to San Antonio in March is currently the most expensive (average of $376). There are several factors that can impact the price of a flight, so comparing airlines, departure airports and flight times can provide users with more options.

January

$303

February

$318

March

$376

April

$338

May

$329

June

$374

July

$351

August

$298

September

$288

October

$298

November

$315

December

$313

Temperature and rainfall in San Antonio by month

Plan your trip to San Antonio by taking into account the average temperature and rainfall totals by month.

SAT

Temperature

51.8 - 84.2 °F

Reviews of airlines servicing San Antonio

Get insights into the airlines that provide service to San Antonio. Read reviews, discover amenities, and learn about the overall travel experience offered by airlines. Use this information to make informed decisions when choosing an airline for your flight to San Antonio. Reviews last updated April 18, 2024.
To help decide which airline to fly from Fayetteville to San Antonio, see what other customers have to say about American Airlines and Delta. Reviews also offer insight into each airline's entertainment options, comfort, food, crew/service, and boarding process.
8.1
Very good
11,104 reviews

Overall

8.1

Comfort

7.9

Entertainment

8.0

Boarding

8.2

Food

7.5

Crew

8.6

Reviews

1 / 10

I love the seamless way that delta ensures that my luggage is on board the plane, I get a notification that it's on board. I love boarding process, orderly and on time. Lots of room in Comfort plus and getting upgraded to first class was everything!

8.1
Very good
11,104 reviews
8.1
Very good
11,104 reviews

Overall

8.1

Comfort

7.9

Entertainment

8.0

Boarding

8.2

Food

7.5

Crew

8.6

Reviews

1 / 10

I love the seamless way that delta ensures that my luggage is on board the plane, I get a notification that it's on board. I love boarding process, orderly and on time. Lots of room in Comfort plus and getting upgraded to first class was everything!

7.3
Good
14,963 reviews
8.1
Very good
11,104 reviews

Overall

8.1

Comfort

7.9

Entertainment

8.0

Boarding

8.2

Food

7.5

Crew

8.6

Reviews

1 / 10

I love the seamless way that delta ensures that my luggage is on board the plane, I get a notification that it's on board. I love boarding process, orderly and on time. Lots of room in Comfort plus and getting upgraded to first class was everything!

Related info for your journey

Find useful and relevant information for your journey from Fayetteville to San Antonio. Access travel guides, tips, and recommendations to enhance your travel experience. Get information about local attractions, weather, transportation options, and more.
  • Can I find flights from Fayetteville, North Carolina to San Antonio for under $300 on Cheapflights?

    Yes, there are multiple flights from Fayetteville, North Carolina to San Antonio for under $300. The cheapest flight booked recently is on American Airlines for just $273, but on average you can expect to pay $445.

  • Are there last-minute flights available from Fayetteville, North Carolina to San Antonio for under $400?

    There are currently 14+ open flights from Fayetteville, North Carolina to San Antonio within the next 7 days for less than $400.

  • What are the cheapest airlines flying from Fayetteville, North Carolina to San Antonio round-trip?

    Cheapflights users have booked flights from Fayetteville, North Carolina to San Antonio round-trip from $273. Another airline that can offer you cheap pricing is Delta. You may be able to fly from Fayetteville, North Carolina to San Antonio for 36% less than the average price by searching for these airlines.

  • What does FAY to SAT mean?

    This is defined as Fayetteville Airport (FAY) and San Antonio Airport (SAT). Codes like San Antonio Airport are often used to just call airports uniquely.

  • Can I find deals for flights from Fayetteville to San Antonio that include extra baggage allowance?

    The amount of baggage you can bring on your Fayetteville to San Antonio flight depends on the airline and the type of fare you've chosen. After entering your flight details, you'll be able to view the specific baggage policies for each deal in the search results. Keep in mind that certain deals may offer additional baggage allowance.

  • Can I find deals on flights from Fayetteville to San Antonio with specific airlines?

    Yes, Cheapflights allows you to browse and filter Fayetteville to San Antonio flight deals by airline. After entering your origin and destination, use the available filters to view flights offered by airlines.

  • Can I find deals for flights from Fayetteville to San Antonio that include hotel bookings?

    Yes. In addition to deals on Fayetteville to San Antonio flights, Cheapflights offers vacation packages that include both flights and hotel.

  • How can I find direct flights from Fayetteville to San Antonio?

    After entering your origin and destination, apply the non-stop filter on the search result page to find direct flights from Fayetteville to San Antonio.

  • Can I find deals for business class flights from Fayetteville to San Antonio?

    Yes. Cheapflights offers flight deals from Fayetteville to San Antonio by cabin class. In addition to browsing deals, you can also filter by cabin class on the search results page after making a search.

  • Can I find deals for flights from Fayetteville to San Antonio that allow pets onboard?

    Many airlines flying from Fayetteville to San Antonio offer the option to travel with pets. After selecting a flight deal, you can find more information about the airline's pet policy on their official website or by contacting the airline directly. Please note that additional fees and restrictions may apply.

  • Can I find deals on last-minute flights from Fayetteville to San Antonio?

    Yes, you can often find last-minute deals on Fayetteville to San Antonio flights on Cheapflights. However, these deals can vary and may not always be available. We recommend checking back frequently or signing up for price alerts for the most up-to-date deals.

  • How recently were the Fayetteville, North Carolina to San Antonio flight deals updated?

    The Fayetteville, North Carolina to San Antonio flight deals you see on this page were last updated on 4/18.

See more FAQs

Browse thousands of different options on Cheapflights for your next trip

Toggle through the tabs below to find thousands of options on Cheapflights for your next trip.

Alternative routes for Fayetteville to San Antonio
See prices for flight routes from nearby airports that may be better suited for you.

Top 2 airlines flying from Fayetteville to San Antonio

Discover the top 2 airlines that operate flights from Fayetteville to San Antonio. Compare their services, reliability, and customer satisfaction ratings to choose the airline that best suits your travel preferences and needs. Over the last 7 days, Cheapflights users made 3,192,047 searches. Data last updated April 18, 2024.
AirlineCheapestAverageFlexibilityOn-time
American AirlinesCheapest$249Average$403FlexibilityNo cancel feeOn-time71%
Search American Airlines flights
DeltaCheapest$257Average$382FlexibilityNo cancel feeOn-timeN/A
Search Delta flights

Search flights from Fayetteville to San Antonio by cabin class

Find flights from Fayetteville to San Antonio, based on your preferred cabin class, be it economy, premium economy, business, or first class.

Fly with Cheapflights

Find the best flight deals on Cheapflights, where travelers can enjoy low prices and a wide availability of flights to their desired destinations.

How does Cheapflights help users find flights from Fayetteville to San Antonio?

When you search for this flight from Fayetteville to San Antonio, Cheapflights searches on 900+ travel sites to save you time finding great flight deals online. Additionally, we offer filter features so you can choose a preferred cabin class or airline, see different price ranges, and much more so you can book the flight for you.

Why should you use Cheapflights to find cheap flight tickets from Fayetteville to San Antonio?

It’s simple! Cheapflights, which is free to use for everyone, saves millions of users time and money every year by helping them find the cheapest and most suitable flights from Fayetteville to San Antonio.

Can Cheapflights find flights from Fayetteville to San Antonio with no change fees?

Need flexible booking options for your flight to San Antonio from Fayetteville? Don’t worry, Cheapflights have you covered. Use our search filter to only show flights with no change fees.

Can Cheapflights notify me if prices for flights from Fayetteville to San Antonio become cheaper?

Not ready to book yet? You can track prices for flights from Fayetteville to San Antonio on Cheapflights with our Price Alert feature and get notified when better prices are available.

100% Free
Cheapflights is completely free to use, so you can start saving the moment you arrive.
Book with Flexibility
Our users can plan ahead with confidence and find flights with no change fees
Travel Smart
Millions of people come to us for their flight needs every year. We help make travel planning easy by providing useful insights and data-driven graphs that can inform your decisions.