# Building Atoms and Isotopes vs CDL Prep A+

The clearest difference is price: CDL Prep A+ at Free against Building Atoms and Isotopes's $1.99. CDL Prep A+ also leads on update cadence (every 5 weeks vs every 18 months). Building Atoms and Isotopes's advantage is in-app purchases (none vs 2) and iOS requirement (13.0 vs 16.0). On ads and device support there is nothing between them.

CDL Prep A+ is free to download; Building Atoms and Isotopes costs $1.99 up front. CDL Prep A+ sells 2 in-app purchases, starting at $8.99 per month. Building Atoms and Isotopes asks for nothing beyond the download.

Building Atoms and Isotopes ships an update every 18 months, CDL Prep A+ every 5 weeks. The most recent releases landed on September 17, 2026 and September 19, 2026 respectively.

## The numbers

| Metric | Building Atoms and Isotopes | CDL Prep A+ |
| --- | --- | --- |
| Price | $1.99 | **Free** |
| Rating | **[3.5 (2 ratings)](https://appshunter.io/ios/app/building-atoms-and-isotopes/id436996679/reviews)** | — |
| Number of ratings | **2** | — |
| Positive reviews | 33.3% of reviews | — |
| In-app purchases | **No** | Yes |
| Ads | No | No |
| Update frequency | Every 18 months | **Every 5 weeks** |
| Monetization | Paid | — |
| Size | 10 MB | 13 MB |
| Requires iOS | **13.0** | 16.0 |
| Devices | **iPhone, iPod** | iPhone |
| Age rating | 4+ | 4+ |
| Developer | [Carolina Biological Supply](https://appshunter.io/developer/413708533) | [Cargo Teleport Inc](https://appshunter.io/developer/1761832181) |

## What reviewers say

### Building Atoms and Isotopes

[App page](https://appshunter.io/ios/app/building-atoms-and-isotopes/id436996679)

Explore the composition of elements by building atoms, ions, and isotopes. Select the correct number of protons, neutrons, and electrons. Includes atomic theory information and an interactive periodic table on iPad.

**Highlights:** Build atoms, ions, and isotopes, Select protons, neutrons, and electrons, Atomic theory information, Interactive periodic table (iPad), Element composition exploration

**Features:** macOS Compatibility

**In-app purchases:** none


### CDL Prep A+

[App page](https://appshunter.io/ios/app/cdl-prep-a-plus/id6736498207)

**Features:** macOS Compatibility

**In-app purchases (2)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Premium monthly subscription | $8.99 | per month |
| Lifetime version | $14.99 | one-time |


## Frequently asked questions

### Is Building Atoms and Isotopes free?

Building Atoms and Isotopes costs $1.99, with no in-app purchases.

### Is CDL Prep A+ free?

CDL Prep A+ is free to download, with in-app purchases available.

### Do Building Atoms and Isotopes or CDL Prep A+ have ads?

Neither Building Atoms and Isotopes nor CDL Prep A+ shows ads.

### Which is updated more often, Building Atoms and Isotopes or CDL Prep A+?

Building Atoms and Isotopes ships an update every 18 months, and CDL Prep A+ every 5 weeks. Most recently, Building Atoms and Isotopes was updated on September 17, 2026 and CDL Prep A+ on September 19, 2026.

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*Compared by [AppsHunter](https://appshunter.io/) from daily US App Store data. Review summaries are generated from verbatim App Store reviews.*