Open location is defined in Standard Additions and should not be enclosed in a tell statement.
open location "http://google.com"
If you want to target a specific browser you can use:
tell application "Safari"
if not (exists document 1) then reopen
set URL of document 1 to "http://google.com"
end tell
To target Chrome:
tell application "Google Chrome"
if not (exists window 1) then reopen
set URL of active tab of window 1 to "https://www.google.com/"
end tell