Use the cmd-9 tab-switching shortcut like Chrome does, by switching to the last tab instead of the ninth tab.
Install the package using Atom's package manager,
$ apm install cmd-9
After installing, reload your editor using
ctrl+alt+cmd+l and your shortcut
should be adjusted for you.
MIT. See LICENSE.md for details.
Good catch. Let us know what about this package looks wrong to you, and we'll investigate right away.