If the child lives with me on weekends can I claim her as a dependent

if the child meets these qualifying child tests you can claim her.

• Child is related to you
•  Same principal abode as taxpayer for more than ½ the tax year.  Temporary absences like for school are ignored
• If not a full-time student, under 19 at the end of the tax year.  If a full-time student under 24 at end of tax year.  

Full -time means an individual who during each of 5 calendar months during the calendar year in which the taxable year of the taxpayer begins is a full-time student at an educational organization described in section 170(b)(1)(A)(ii), or is pursuing a full-time course of institutional on-farm training under the supervision of an accredited agent of an educational organization described in or of a State or political subdivision of a State.

• Hasn’t provided over ½ his/her own support

or if the child meets the qualifying relative tests 

Qualifying Relative

• meets relationship test or lives with taxpayer for the entire year
• gross income for 2019 less than $4,200
• you provide over ½ his support
• isn’t a qualifying child of another taxpayer