Arduino: 1.8.1 (Mac OS X), Board: "Arduino/Genuino Uno"
Sketch uses 1778 bytes (5%) of program storage space. Maximum is 32256 bytes.
Global variables use 31 bytes (1%) of dynamic memory, leaving 2017 bytes for local variables. Maximum is 2048 bytes.
avrdude: ser_open(): can't open device "COM1": No such file or directory
Problem uploading to board. See http://www.arduino.cc/en/Guide/Troubleshooting#upload for suggestions.
This report would have more information with
"Show verbose output during compilation"
option enabled in File -> Preferences.
That's actually an error uploading. The verification(compilation) completed successfully or it wouldn't have gotten this far.
You need to select the COM port of your Arduino from the Tools > Port menu. If the Arduino doesn't appear on the menu or the menu is grayed out then you may need to install the driver for your Arduino.
On a Mac you won't normally get a COM1 as serial port.
My Mac shows something like:
Tools / Port: "/dev/cu.usbserial-..."
If you don't see something similar on your Mac your board is not detected by the OS and you need to install the right driver for it.
Questions:
What Arduino hardware -> original one or a Chinese clone? If the latter you might need a CH340 driver.
What OSX version do you have installed? If Sierra -> use the search function in the forum to look for solutions as there are problems with Sierra and FTDI drivers (if you got an original Uno).